DE1427644A1 - Method and device for the continuous coating of, in particular, endless metal strips with a plastic layer - Google Patents

Description

1427G44

Method and apparatus sura continuous read chi rushed from Particularly endless metal edges with a 'plastic face

The present invention relates to. a procedure- 'as well as on a device for bubble-free application and rapid curing of thin plastic layers that are liquid or pulpy State in a steady operation to continuously scrolling endless belts, especially metal oxides :! '. to be applied »

There are various ways of producing such plastic support layers Methods and devices known. The older known methods and devices are such that the one provided for the: 3e layering Plastic compound is first plasticized on a screw press and then continuously formed into a plastic film using a slot die pulled out and then on the coating parts by several, with each other cooperate: -de press orphans underarming effect on the Base is rolled on. Such Beschlchtungsvorrichtungeii with a The associated complete foil installation have the disadvantage that the entire system is very expensive and space consuming, and that the Working speed is relatively slow, since the pulling, In particular, thin films can only be achieved slowly. Another shortcoming that also exists when the coating film beforehand at any point regardless of the coating direction manufactured is the fact that only such plastic compounds are to be processed from which flawless films can be produced. In addition, the greater the width of the technical effort for film production disproportionately high

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1S27P44

In the more modern B ^ schichfmngsijeGhnik-have learned about it enforced, in which the Beschiohtünßsmaterial. in the liquid state, for example, resolved in a solution, in pinge », ¥ DJ? ge. · written layer thickness on the tape-shaped guided over rollers Pad is applied. The coated tape then passes through Heating or cooling devices to evaporate the solvent., Where the applied layer gels bp, hardens resp. is polymerized.

In addition to some internal disadvantages, for example blistering in the application sheet or contamination of the application chip due to ■ - · -. Fly dust j brings this. The process entails the difficulty that the freshly coated strip may only be transferred by a supporting or deflecting ring when it is passed through the drying device f when the coating has completely worn out or hardened.

Since tpi already existing systems, which work according to a method as described, the gelation times depend on the. The coating materials to be used and the respective thickness, even with the use of the appropriate packing units, take about 1 to 3 minutes to reach the frqckniingsstreeken, that is, the heating or cooling equipment with the usual ones Tape visibility of about 3Q to 5Q ml / min extremely large; Iiqh large lengths, in the existing systems -are already <Ivq; eknungsanlagen of 60 m length and over known ^ "by the a * h, for example beid-rseltige.sbeschiehtetes band contactless ^ d. must be pulled freely suspended to, Beschädigun8 @ ⁿ of Auftragssehieht to ^r -vermeiden-

j BATH

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Another effective extension of the ^ drying oven or cooling equipment is therefore practically impossible. No further increases in production can therefore be achieved in the known plants Steigerun «; the belt speed can be achieved.

The invention aims to eliminate these difficulties and achieves this procedurally in that the provided for coating Plastic, as before, brought into a pulpy to liquid state in a manner known per se by means of a solvent and that the application of this pulpy to liquid Beschlchtungsstoffes on the tape to be coated and curing or the polymerization of the AHffca? ageeiek application layer in a vacuum or at least in a treatment room containing a negative pressure is carried out. · ■

Because the fractional solvent distillation can be reduced in the Vaktt vacuum by lowering the boiling points of the solvents involved, the gelling, drying or polymerization number, which is controlled by the solvent, can be shortened considerably . The common solvents, for example methyl ethyl acetone, evaporate in a normal atmosphere at about 80 C. Even when using a low vacuum, for example between 100 and ko Torr, the boiling point can be shifted to room temperature or lower. This has the advantage that after the evaporation of the solvent, subsequent cooling of ^the coated strip (conventional slime) is no longer necessary. The entire drying: the stroke for curing the coating is therefore shortened, - ^; o there? a v; e'Lt'j;e;i'r: vie Hrhohun; - der -a

speed and thus an increase in production; becomes possible. In addition to the advantages of greater coating performance, the coating materials are applied in a vacuum, bubble-free and dust-free. In / out resulting in te Vakxiumbehandlung advantages in the V / e ice that formed during the evaporation of the solvent - '''solvent vapors are condensed / facilities by appropriate cooling and can be captured again. This can significantly reduce the solvent consumption. Another advantage of the vacuum coating according to the invention is that the 'material norms in and out of the belt surface are free of air through the evacuation', whereby a suction effect occurs when the coating materials are applied, which leads to better adhesion of the applied layer. In various cases, it is therefore possible to dispense with a pretreatment of the Leschichtuiigsguts with an adhesion promoter. Furthermore, when coating light metals, for example aluminum strips, there is an advantage: the fact that there is no change in the technological Properties of the aluminum strip is brought about because the drying takes place in the "^ akuum below the recrystallization temperature. .

Finally, compared to conventional coating systems, a significantly lower energy consumption is also advantageous, because only the heat of evaporation removed during the evaporation of the solvent needs to be returned. This supply of heat, which is necessary to maintain the evaporation temperature, is: but relatively low, since, as already said, the evaporation; . The temperature of the solvents in a coarse vacuum is around room temperature. V 80 9 8 08/0 02 I ν '■ ■ -. BATH ORIGINAL

The device for carrying out the method according to the invention, which has a vacuum chamber serving for vacuum treatment, which is connected to both the strip inlet side and the strip outlet side in a known manner sealed airtight by liquid containers wirdy is characterized by the fact that in the same plane as the Liquid sealing filters and further treatment containers are provided between these and that the liquid separating containers - Each via a Yerbinduntrsrohr, the treatment tank against it each via two connecting pipes with one in a second level Above arranged vacuum vessel are connected in such a way that the tape to be coated in several vertical loops through the device can be passed through, both of which are leading the tape Deflection rollers as well as the actual coating devices partly are arranged in the containers and partly in the vacuum vessel.

The system costs are extremely low compared to conventional systems due to this simple structure of the device. Due to this arrangement, the vacuum space is kept very small in relation to its intended use and the vertical pipe connection of the liquid drainage container with the upper vacuum vessel makes it possible to set up an arbitrarily high vacuum, since the liquid column sucked in by the vacuum can rise as far as desired in these connecting pipes. Regardless of the level of the vacuum, a continuous strip passage through the device is therefore given. The Flttssigkeitsabflussbäder can serve as treatment baths, for example in the manner that the liquid at the completion Bandelwerk running side of the device is also the last purification step a band pre-treatment, while through the liquid-809808/0021 _ ₆ _ BAD

At the same time, an aftertreatment is carried out on the strip exit side of the finished tape, for example in such a way that the coated tape is covered here with a thin protective film an electrostatic charge and thus an attraction to dust impede.'

These and other details of the method according to the invention as well as * the device according to the invention selenium on the basis of an exemplary embodiment, which is reproduced in the accompanying drawings, explained in more detail.

Show in detail:

Figure, 1 is a front view of the device according to the invention,

Figure 2 is a schematic representation of a known per se Loading device,

FIG. 3 shows a section along the line II-II of FIGS. 1 and FIG. 4 shows a section along the line III-III of FIG.

The device shown in the embodiment for vacuum

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coating of continuously running endless belts consists-essentially of four containers 1, 2, 3, 1, 2, 2, 3, 1 set up next to each other on one level, as well as one on a second level above arranged vacuum vessel 5 and six vertically extending Connecting pipes 6,7,8 ^ 9,10,11 through which the lower holders 1,2,3,4 be connected to the vacuum tank 5. In order to have a flawless - i.e. vacuum-tight closure of the connecting pipes -e, ·?, 8,9,10,11 to. are on each of the un © iron containers Ii.2, ^ 4 two at a time

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upwardly directed pipe socket a and b attached, while the upper Vacuum vessel 5 six downwardly directed pipe sockets c, d, e, f, g and ή owns. The connection of the lower container 1,2,3,4 with the upper vacuum vessel 5 is by means of the connecting pipes 6,7,8,9 10, 11 taken so that the strip to be coated 12 on the inside the container 1,2,3,4 arranged lower deflecting rollers 13,14,15,16 or, via the upper guide rollers 17,18,19 mounted in the vacuum tank 5 passed through the device in several vertical loops can be. The open pipe socket 1a of the container 1 is used here as the inlet into the device and the pipe socket 4b of the container 4 al8 outlet from the device. The tape infeed roller 20 and the Belt discharge roller 21 are located approximately at the same height outside the actual device.

All foil of the device, i.e. the containers, the vacuum vessel and the connecting pipes can be of any cross-section, So they can also be made square or rectangular. Since the If the device is evacuated by the internal vacuum, but heavy loads occur, you will be in the _ In most cases, choose a round or at least oval cross-sectional shape. The vacuum is generated by separately installed vacuum generators not shown in the drawings, e.g. Pumps, steam jets, condensers or the like .. Not about either The pipelines shown are these vacuum generators via the boiler drains 22 connected to the upper vacuum vessel 5.

The containers 1 and 4 both serve as a liquid container for receiving the liquid seal and are thus at the same time locks for

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the air-free strip entry or exit. In both cases, the sealing medium is an aqueous solution. The solution in the container 1 _S ie at the Bandeinlaüfseite can include clothes nor the last purification stage of BandvorbehandL. In contrast, the solution in the container 4 can be a feeding solution which, when the coated tape passes through, leaves a protective film on the surface of the tape, by means of which an electrostatic charge and thus the attraction of dust is prevented. , ·

During operation, depending on the level of the vacuum in the device, the solutions in the containers 1 and 4 are drawn up into the vacuum space _/ ie into the connecting pipes 6 and 11, in the connecting pipes 6 and 11, a dem Vacuum a corresponding column of liquid. Overflow nozzles are also provided on the containers 1 and, through which the solutions in the containers drain into a lower-lying collecting container (not shown in the drawing) in order to be pumped back into the container via the pipe connections 1a or 4b, which are open to the air atmosphere will. This has the advantage that the liquid level in the containers 1 and 4 always maintains a constant level, even if unintentional fluctuations should occur in the vacuum. In addition, in this way the composition of the solution can always be checked and, if necessary, supplemented or renewed.

The containers 2 and 5 serve as treatment containers and are below Vacuum. In addition to the lower belt deflection rollers 14 or 15 " the actual coating devices 25 and 26 for application an adhesion promoter or the plastic layer. The same

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In addition, looping devices are again in the vacuum tank 5 provided, the loading device 27 for applying a Adhesion promoter and the coating device 28 for applying the Plastic layer are intended.

A coating device (see FIG. 2) consists of a tub 40 containing the liquid plastic or adhesion promoter, a dip roller 41 immersed in the tub and an application roller 42 that works together with the dip roller. The entire unit including its drive is in the vacuum space stored and each arranged in the area of a deflection roller 14, 25 or 17 * 18 guiding the belt 12, so that the deflection roller serves as a counter-pressure roller when the plastic layer is applied. In order to be able to set the thickness of the application precisely during the coating, the entire coating device can be displaced towards the belt, that is to say towards the center of the deflecting roller. The tubs 40 containing the liquid plastic each have an overflow and an inlet connection. These connections are connected to a storage container which is arranged outside and below the vacuum system. So that the coating materials do not dry out and their viscosity is retained, they are continuously pumped around. In order to maintain the vacuum, however, it is necessary that the connection lines form a U-shaped loop that runs vertically downwards, corresponding to the height of the vacuum, in order to cancel the suction generated by the vacuum.

The container bottom of the treatment container 2 and 3 are designed so that when working with a coarser vacuum for example over 100 Torr that on the cooler pipe walls of the pipes 7,8,9, and

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condensing and refluxing solvents are collected at the bottom can be. By special drain lines 29 and 50, the condensate is sat and the condensate level in tanks 2 and 5 kept constant. The leads 29 and 50 are similar to the connection lines of the coating devices are U-shaped vertically downwards, the length of the U-shaped loop must be adapted to the vacuum level. For proper condensation of the evaporated solvent can in the treatment tanks 2 and optionally cooling devices, for example cooling coils 51, are provided. However, external cooling of the container is also possible 2, 5 or the connecting pipes 7 * 8,9,10 possible.

The treatment or coating - of the strip 12 - takes place as described, in the treatment tanks 2.5 or in the vacuum tank 5 * The connecting pipes 6 to 11 serve as a drying room for drying and harden the coating material so that through the length of the connecting pipes the length of the drying section is to be determined, so by extending the connecting pipes the length of the drying section can be extended in a very simple and cheap way without the Other components of the device need to be changed. With The connecting pipes connected to the liquid containers 1 and 4 6 and 11 also serve as risers for the vacuum suctioned liquid columns of the sealing medium.

The drying or hardening or polymerisation of the freshly applied To accelerate the coating and at the same time to replace the heat dissipated by the evaporation of the solvents * are in

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heating devices 32 are installed in the connecting pipes. Because the heat supply Can only be done by radiation in a vacuum are preferred Infrared radiators or similar heat radiators provided «The heating devices are in each case close to the strip surface that has just been coated and are set up in such a way that intensive irradiation is possible of the coating materials is possible.

An example of an embodiment of a heating device designed as a heat radiator is shown in FIGS. 3 and 4. The heat radiators 33 are each combined into groups, with a radiator group consisting of several tubes 34 arranged transversely to the direction of belt passage, which are welded vacuum-tight to the connecting tube, for example tube J ₁ - The radiant heat pipes Jjk have free passage on both sides inside, so that any heat source can be installed or connected. To reinforce and intensify the radiation effect, reflectors 35 are provided on the side of the radiant heat tubes 34 facing away from the strip 12.

If the connecting pipes J to 10 are provided with such radiant tubes 34 over their entire lengths, they can be used either for heating or for cooling.

The workflow or the coating ^ process in the invention The device is as follows: The strip 12 to be coated is ta in via the strip inlet roller 20 through the open pipe socket the liquid container 1 is introduced and passed up into the connecting pipe 6 through the deflecting roller 13 mounted in the liquid.

BATH £ 0980 ^ / 0021

In the upper part of the connecting pipe 6 is one as described Heater 32 built in to through adhesion to the belt surface stuck water droplets evaporate. When redirecting of the belt 12 around the upper deflecting roller I7 is fed through the feeder 25 an adhesion promoter on one side of the tape applied. As the belt continues, this release layer becomes through the heating device 32 located in the connecting pipe 7, radiates, the solvent evaporates and the layer itself dries out. In the treatment tank 2 is then by means of the coating device 26 the other side of the tape is provided with an adhesion promoter, which when the tape starts up again in the connecting pipe is dried. When the belt revolves around the upper deflection roller the first side of the hinge is now coated with a plastic that as it continues through the connecting pipe 9 with the aid of the there Heater J2 hardens or polymerizes. In the treatment tank then takes place during the rotation around the deflection roller 15, the plastic coating of the second band side and in the connecting pipe 10 the Curing or polymerization. Through the upper deflection roller 19 is the band 12 is deflected downwards again and dips into the liquid seal of the liquid container 4 in the connecting pipe. To Deflecting the tape by the stored in the liquid container 4 The lower deflection roller 16 then leaves the belt through the open one Pipe socket 4b the device in order to be discharged via the belt discharge roller 21 to become.

It is understood that those described here and in the drawings The embodiment shown schematically is only to be considered as an example. Modifications can be made at any time without the concept of the invention # i

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or to change or leave the scope of the invention. So can for example immediately in front of the plastic layer applying Coating devices 27, 28 again heat radiation devices be provided in order to slightly soften the respective already applied adhesion promoter layer by heating. Depending on the consistency the coating materials can thereby improve the adhesion of the plastic layer be achieved.

BATH 809808/0021

Claims (1)

1427G44 Patent claims 1. Process for bubble-free application and rapid curing of thin 'plastic layers that are in a liquid or pulpy state in a steady operation to continuously ^ continuous endless belts, especially metal belts, are applied, characterized in that the for coating certain plastic in a known manner by means of a Solvent brought into a pulpy to liquid state and that the application of this pulpy to liquid coating material on the strip to be coated and the curing or polymerisation of the coating layer in a vacuum or at least carried out in a treatment room containing a negative pressure will. 2. The method according to claim 1, characterized in that g e k e η η ζ e i c h η e t, that the level of vacuum or negative pressure is set up so that the evaporation temperature of the solvent is about room temperature lies, 5. The method according to Anspizüehen 1 and 8, d a d u r c h g e k e η η ζ ei c h η e t that the evaporation of the solvent Heat of evaporation dissipated by radiation to be introduced from the outside heat is replaced. %. Device for carrying out the method according to Claims 1 to 5, in which the vacuum space used for the vacuum treatment passes through both the strip inlet and the strip outlet side 09808/0021 BAD ORIGINAL Liquid container is hermetically sealed, thereby marked without t that in the same plane as the liquid closure container (1,4) and between these further treatment containers (2,5) are provided and that the liquid closure container (1,4) each via a connecting pipe (6,11), the treatment tank (2,5), however, each via two connecting pipes (7,8; 9,10) with a vacuum vessel (5) arranged on a second level above are connected in such a way that the strip (12) to be coated can be passed through the device in several vertical loops, both the guide rollers (15 to 19) leading to the belt (12) and the actual coating devices (25 to 28) partly in the containers (1 to 4) and partly in the vacuum vessel (5) are arranged. 5. Apparatus according to claim 4, characterized in that the connecting pipes (6, 11) connecting the liquid closure container (1,4) to the vacuum vessel (5) simultaneously serve as riser pipes for the liquid columns of the sealing medium sucked in by vacuum, while the connecting pipes (7 to 10) between the treatment containers (2.5) and the vacuum vessel (5) serve as a drying space or as a % drying section for curing or polymerizing the plastic coating. 6. Device according to claims 4 and 5, characterized in that that in the connecting pipes (6 to 10) serving as drying rooms heating devices (52), for example heat radiators such as infrared emitters, are installed near the surface of the belt. 7. Device according to claims 4 to 6, characterized 809808/002 1 indicates that for condensation of the evaporated solvent * cooling devices preferably arranged in the treatment containers (2, 5) (J51) are provided, the treatment tanks (2, 3) also serving as a collecting tank for the condensate and with a discharge line (29,30) that maintains the vacuum for discharge of the condensate are provided. 8. Device according to claims 4 to 7 * characterized in that the coating devices (25 to 28) in the Area of the belt (12) leading Urnlenkwalzen (17 * 14,18,15) arranged are, so that in a coating, for example by means of Application rollers (42) which serve as counter-pressure rollers. 9. Device according to claims 4 to 8, characterized g e k e η nz e i c h η e t that the liquid closure baths at the same time as Treatment baths are used and appropriate depending on the requirements Contain treatment substances (solutions). 10. Device according to claims 4 to 9> da d u r c h g -e k e η η-. draw t that the length of the drying distance for curing or polymerize the plastic coating layer of the length of the Connection pipes (6 to 11) is dependent. BATH ORIGINAL 8 0 9 8 0 8/0 0 2 1