EP2739923B1 - Method and device for drying a fluid film applied to a substrate - Google Patents

Description

The invention relates to a method and a device for drying a fluid film applied to a substrate, which contains a vaporizable liquid, according to the preamble of patent claims 1 and 15.

Such a method and such a device are known from US 2007/110894 A1 known.

According to the prior art, it is also known to coat the surfaces of web-shaped goods. The web-shaped goods may be, for example, paper, plastic films, textiles or metal strips. To coat the surface, a fluid film is applied which contains a vaporizable liquid and non-volatilizable components. The fluid film is solidified by evaporation of the vaporizable liquid. This process is called drying of the fluid layer.

For solidification or drying of the fluid film, it is for example from the DE 39 27 627 A1 It is known to flow both a lower side of the substrate and an opposite upper side provided with the fluid film with a heated drying gas. At one of the DE 39 00 957 A1 known method, a drying gas flowing along the surface of the fluid film is accelerated in the flow direction. The abovementioned drying methods have the disadvantage that unwanted mottling phenomena occur on the surface of the fluid film due to the action of the drying gas.

To overcome this disadvantage, it is from the WO 82/03450 It is known to provide a flow-through filter layer at a distance above the fluid film. Due to the effect of the filter layer, the flow of the drying gas in the area above the fluid layer is slowed down and turbulent flows are thus avoided. As a result, however, a liquid vapor escaping from the fluid film can not be dissipated particularly quickly. This drying process is not very efficient.

In the drying process known from the prior art, large volumes of drying gas are required, which subsequently have to be laboriously cleaned and / or regenerated.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, a method and a device are to be specified with which a fluid film applied to a substrate can be dried while avoiding mottling phenomena and with improved efficiency, without having to move large amounts of air.

This object is solved by the features of claims 1 and 15. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 14 and 16 to 25.

According to the invention, in a method for drying a fluid film containing a vaporizable liquid applied to a substrate surface of a substrate, it is proposed that the heat from the heating surface to the fluid film be transferred substantially by direct heat conduction.

In the proposed method, the departure from the prior art, the liquid is substantially evaporated by means of a heat source provided opposite the substrate. This eliminates the effort to heat the drying gas. The further effort for cleaning or regeneration of the drying gas can be significantly reduced. With the method proposed according to the invention, drying rates of up to 20 g / m ² s can be achieved. This corresponds to about 10 times those drying rates, which are achieved by the methods known in the prior art.

Since the heating surface of the heat source is arranged only at a distance of 0.1 mm to 15.0 mm, preferably 0.2 to 5.0 mm, opposite the substrate surface, the heat in the method according to the invention is supplied to the fluid film essentially by direct heat conduction , This advantageously ensures that the fluid film is heated from its surface facing the heating surface in the direction of the substrate surface. In contrast to the entry of heat by means of heat radiation, which is absorbed substantially at the substrate surface, thus a particularly effective evaporation or diffusion of the liquid can be achieved.

Furthermore, the vaporized liquid is removed in the direction of the heat source by the applied temperature gradient. Ie. the vaporized liquid flows substantially perpendicularly from the interface and then enters a channel formed by the interface and heating surface. It is largely avoided within the fluid film, the generation of a substantially parallel to the interface directed flow with high amounts of air. As a result, step no mottling phenomena in the fluid film in the method according to the invention.

According to a further particularly advantageous embodiment of the invention, a gas flow is generated in the channel formed between the heating surface and the interface for discharging the evaporated liquid opposite to the transport direction of the substrate. The gas flow may be generated, for example, by a suction device which is provided at the upstream end of the channel. Thus, the evaporated liquid is moved in the direction of each upstream upstream heat source. A flow rate of the gas flow guided in the opposite direction to the transport direction of the substrate is expediently 2 cm / s to 30 m / s, preferably 10 cm / s to 10 m / s. The flow rate of the gas depends on the length of the channel and the amount of liquid to be evaporated. If the liquid to be evaporated is flammable, choose an inert gas as the gas.

According to an advantageous embodiment, a first temperature T _{G of} the heating surface is regulated as a function of an interface temperature T _{I of} the fluid film. The first temperature T _G is adjusted so that the required removal of the released fluid vapor is ensured by the surface. The heat is advantageously transferred from the heating surface to the fluid film essentially by direct heat conduction.

The first temperature T _G is suitably controlled in the range of 50 ° C to 300 ° C, preferably in the range of 80 ° C and 200 ° C.

wobei

• T_I im Bereich von 10°C bis 50°C und
• ΔT im Bereich von 10°C bis 40°C, vorzugsweise 20°C bis 30°C, liegt.

According to a further advantageous embodiment, the transport surface is heated by means of a further heat source. A second temperature T _{H of} the transport surface generated by the further heat source is advantageously regulated as a function of the interface temperature T _I. In this case, the second temperature T _{H can} be regulated in particular such that the following relationship is fulfilled: $${\mathrm{T}}_{\mathrm{H}}={\mathrm{T}}_{\mathrm{I}}+\mathrm{.DELTA.T}.$$

in which

• T _I in the range of 10 ° C to 50 ° C and
• ΔT is in the range of 10 ° C to 40 ° C, preferably 20 ° C to 30 ° C.

Due to the evaporation of the liquid there is a cooling of the transport surface. To increase the mass flow of the evaporated liquid, the transport surface is heated to a second temperature T _H by means of a further heat source. In this case, the second temperature T _H is set so that it is greater than the interface temperature T _I. A particularly large mass flow of the evaporated liquid is advantageously achieved when the difference .DELTA.T between the interface temperature T _I and the second temperature T _{H is} in the range of 2 ° C to 30 ° C.

Expediently, the evaporation of the liquid is carried out in a non-combustible gas atmosphere, preferably a nitrogen or carbon dioxide atmosphere. This can be safely and reliably avoided ignition of a vaporized within the drying device combustible liquid.

According to a further particularly advantageous embodiment, the heating surface facing the substrate is arranged at a distance of 0.2 mm to 5.0 mm, preferably 0.2 to 1.0 mm, opposite the substrate surface. The proposed small distance between the heating surface and the substrate surface allows a particularly homogeneous heating of the fluid film and thus a uniform evaporation of the liquid. A thickness of the fluid film is of course chosen so that it is smaller than the aforementioned distance. The fluid film may, for example, have a thickness in the range of 5 μm to 200 μm, preferably 10 μm to 50 μm.

According to a further advantageous embodiment, the second temperature T _H is controlled so that it is always smaller than the first temperature T _G. A temperature difference between the first T _G and the second temperature T _H can in particular be regulated so that a predetermined temperature difference profile is established along the transport device. The temperature gradient or the temperature difference between the first T _G and the second temperature T _H can change along the transport direction in a predetermined manner. This takes into account the fact that the amount of liquid to be evaporated decreases in the transport direction. The change of the temperature gradient can be effected by a suitable regulation of the first T _G and / or second temperature T _H or also by a change of the distance of the heating surface from the boundary surface.

To be particularly advantageous, it has been found that a heat source through which a streamable heat source is used and the evaporated liquid is discharged through the heat source. Thus, the evaporated liquid substantially are discharged vertically from the surface of the fluid film or the interface.

As the heat source, an electric heating source, preferably a heat source equipped with heating elements, is suitably used. In this case, the resistance heating wires can be arranged, for example, like a grid. Furthermore, it is possible to use at least one heat exchanger as the heat source. Such a heat exchanger may be designed to be flowed through like a radiator for motor vehicles. It is also possible to provide a plurality of heat exchangers in succession in the transport direction, it being possible for a gap to be provided in each case between the heat exchangers. Through the gap, the vaporized liquid can be removed from the surface of the fluid film.

According to a further advantageous embodiment of the invention, at least one rotatable roller is used as a transport device, whose lateral surface forms the transport surface. Such a transport device can be made relatively compact. It may also be combined with a slot die tool for applying the fluid film. In the case of using a rotatable roller as a transport device, the heat source is configured corresponding to the lateral surface of the roller, that is, a heating surface of the heat source is arranged at a predetermined small distance from the lateral surface. The further heat source is arranged inside the roller. By means of the further heat source, the transport surface is heated by an underside of the transport device opposite the substrate, preferably by means of direct heat conduction. For example, the transport surface can be electrically heated by means of resistance heating elements. Such an electric heater allows a particularly simple control of the temperature of the transport surface.

According to another aspect of the invention, there is provided an apparatus for drying a fluid film applied to a substrate surface of a substrate comprising a vaporizable liquid, wherein the heat from the heating surface is transferred to the fluid film substantially by direct heat conduction.

The proposed device enables efficient drying of a fluid film applied to a substrate. In this case, the liquid is evaporated by a heat source provided opposite the substrate. The heat source is arranged only at a distance of 0.1 to 15.0 mm, preferably 0.1 to 5.0 mm from the substrate surface. The vaporized liquid is removed by generating a flow directed from the substrate in the direction of the heat source. For this purpose, a device for discharging the evaporated liquid is provided.

According to an advantageous embodiment, a further heat source for heating the transport surface is provided. The further heat source is expediently provided on a "underside" of the transport device opposite the substrate. It may be, for example, a resistance heater.

According to a further advantageous embodiment, a first control device is provided for controlling a first temperature T _G generated by the heating surface as a function of an interface temperature T _{I of} the fluid film. The controlled variable, namely the first temperature T _{G of} the heating surface, is determined according to a predetermined algorithm depending on the interface temperature T _I , which forms the reference variable set. In this case, the first temperature T _{G can} be regulated, for example, such that a predetermined temperature gradient is formed between the interface temperature T _I and the first temperature T _G.

Furthermore, a second control device is advantageously provided for controlling a second temperature T _{H of} the transport surface as a function of the interface temperature T _I. In this case, the interface temperature T _I is measured as a reference variable. Depending on the measured interface temperature T _I , the second temperature T _{H is} adjusted or tracked by means of the control device. The setting or the tracking of the second temperature T _{H is} expediently such that a predetermined interface temperature T _{I is} kept substantially constant.

The first T _G and the second temperature T _H can be measured, for example, by means of conventional thermocouples. The interface temperature T _I can be detected without contact, for example by means of an infrared measuring device.

The first control device can also be omitted. In this case, the first temperature T _{G is} kept constant. The first and the second control device can also be coupled. A temperature gradient between the first T _G and the second temperature T _H can be regulated in accordance with a further predetermined algorithm so that along the transport direction a predetermined temperature difference profile is established between the transport surface and the heating surface.

Because of the advantageous embodiment of the device, reference is made to the description of the embodiments of the method. The design features described procedurally form mutatis mutandis embodiments of the device.

Fig. 1

eine schematische Darstellung zur Erläuterung der in den Formel verwendeten Größen,

Fig. 2

die Grenzflächentemperatur über der Gastemperatur bei vorgegebener Transportflächentemperatur,

Fig. 3

die Grenzflächentemperatur über der Transportflächentemperatur bei vorgegebener Gastemperatur,

Fig. 4

die Massendiffusionsrate über der Gastemperatur bei vorgegebener Transportflächentemperatur,

Fig. 5

die Massendiffusionsrate über der Transportflächentemperatur bei vorgegebener Gastemperatur,

Fig. 6

die Trocknungsdauer über der Gastemperatur bei vorgegebener Transportflächentemperatur,

Fig. 7

die Trocknungsdauer über der Transportflächentemperatur bei vorgegebener Gastemperatur,

Fig. 8

eine schematische Schnittansicht durch ein Ausführungsbeispiel eines erfindungsgemäßen Diffusionstrockners,

Fig. 9

eine schematische Detailansicht gemäß Fig. 8 und

Fig. 10

eine schematische Schnittansicht durch ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Diffusionstrockners.

The invention will be explained in more detail with reference to the drawings. Show it:

Fig. 1

a schematic representation for explaining the sizes used in the formula,

Fig. 2

the interface temperature above the gas temperature at a given transport surface temperature,

Fig. 3

the interface temperature above the transport surface temperature at a given gas temperature,

Fig. 4

the mass diffusion rate above the gas temperature at a given transport surface temperature,

Fig. 5

the mass diffusion rate over the transport surface temperature at a given gas temperature,

Fig. 6

the drying time above the gas temperature at a given transport surface temperature,

Fig. 7

the drying time over the transport surface temperature at a given gas temperature,

Fig. 8

a schematic sectional view through an embodiment of a diffusion dryer according to the invention,

Fig. 9

a schematic detail view according to Fig. 8 and

Fig. 10

a schematic sectional view through a further embodiment of a diffusion dryer according to the invention.

The theoretical principles of the method according to the invention are briefly explained below with reference to one-dimensional equations for the diffusive mass transport as a function of the temperature.

Out Fig. 1 For example, the quantities used in the following equations are essentially apparent.

The temperature gradient in the air gap above the interface of the fluid film fulfills the energy equation, which can be stated for the gas phase as follows: $$\frac{d^{2}T}{{\mathit{dy}}^2}-\left(\frac{\dot{m}{C}_P}{{\lambda }_G}\right)\frac{\mathit{dT}}{\mathit{dy}}=0$$

wobei c ₁ und c ₂ zwei noch zu definierende Integrationskonstanten darstellen. Diese können über geeignete Randbedingungen bestimmt werden. Diese Randbedingungen sind wie folgt: $$y=0\frac{\mathit{dT}}{\mathit{dy}}{|}_{I/G}=\frac{\left(1-f\right)*\left(T_H-T_I\right)}{\left(\frac{{\mu }_G{\mathrm{\Delta }\mathit{h}}_{\mathit{LH}}}{2T_I}-{\lambda }_G\right)*\left(\frac{H}{{\lambda }_S}+\frac{h}{{\lambda }_L}\right)}$$

$$y={\delta }_G,\mathit{T}=T_G$$

Solving this diffusion equation gives the following general solution: $$T={\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="imgf0005.png"\; state="\{\{state\}\}">c</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="imgf0005.png,imgf0007.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\mathit{exp}\left(\frac{\dot{m}{C}_P}{{\lambda }_G}y\right).$$

where c ₁ and c _{2 represent} two integration constants yet to be defined. These can be determined by suitable boundary conditions. These boundary conditions are as follows: $$y=0\frac{\mathit{dT}}{\mathit{dy}}{|}_{I/G}=\frac{\left(1-f\right)*\left(T_H-T_I\right)}{\left(\frac{{\mu }_G{\mathrm{\Delta }\mathit{H}}_{\mathit{LH}}}{2T_I}-{\lambda }_G\right)*\left(\frac{H}{{\lambda }_S}+\frac{H}{{\lambda }_L}\right)}$$

$$y={\delta }_G.\mathit{T}=T_G$$

Solving the above equations by substituting the boundary conditions for c ₁ and c ₂ , one obtains values for these quantities which indicate the temperature profile in the gas phase as follows: $$T=T_G=\frac{\left(1-f\right)*\left(T_H-T_I\right)*\left\{\mathit{exp}\left(\frac{\dot{m}{C}_P}{{\lambda }_G}{\delta }_G\right)-\mathit{exp}\left(\frac{\dot{m}{C}_P}{{\lambda }_G}y\right)\right\}}{\dot{m}{C}_P*\left(\frac{{\mu }_G{\mathrm{<figure-callout\; id="2"\; label="\Delta \; H\; LH"\; filenames="imgf0005.png,imgf0007.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}\mathit{H}}_{\mathit{LH}}}{2{\lambda }_G{T}_I}-1\right)*\left(\frac{H}{{\lambda }_S}+\frac{H}{{\lambda }_L}\right)}$$

For y = 0 one obtains T = T ₁ . Thus, the interface temperature T ₁ , ie the temperature at the free surface of the fluid film, can be calculated as follows: $$T_I=T_G-\frac{\left(1-f\right)*\left(T_H-T_I\right)*\left\{\mathit{exp}\left(\frac{\dot{m}{C}_P}{{\lambda }_G}{\delta }_G\right)-1\right\}}{\dot{m}{C}_P-\left(\frac{{\mu }_G{\mathrm{<figure-callout\; id="2"\; label="\Delta \; H\; LH"\; filenames="imgf0005.png,imgf0007.png"\; state="\{\{state\}\}">\Delta \; </figure-callout>}\mathit{H}}_{\mathit{LH}}}{2{\lambda }_G{T}_I}-1\right)-\left(\frac{H}{{\lambda }_S}+\frac{H}{{\lambda }_L}\right)}$$

The mass diffusion rate per unit area based on the temperature gradient at the free surface can be calculated as follows: $$\dot{m}=\frac{\left(1-f\right)*{\mu }_G*\left(T_H-T_I\right)}{\left({\mu }_G{\mathrm{\Delta }\mathit{H}}_{\mathit{LH}}-2{\lambda }_G{T}_I\right)*\left(\frac{H}{{\lambda }_S}+\frac{H}{{\lambda }_L}\right)}$$

The drying time for the material to be coated can be calculated as follows: $$t_d=\frac{M}{\dot{m}}=\frac{{\rho }_L*H*\left({\mu }_G{\mathrm{\Delta }\mathit{H}}_{\mathit{LH}}-2{\lambda }_G{T}_I\right)*\left(\frac{H}{{\lambda }_S}+\frac{H}{{\lambda }_L}\right)}{\left(1-f\right)*{\mu }_G*\left(T_H-T_I\right)}$$

Through the above set of equations, the one-dimensional diffusion heat transfer problem and the problem of associated mass release and mass transport can be solved analytically.

$$f=0.2,{\mathit{T}}_G=350K,{\mathit{T}}_H=295K$$

Using the boundary conditions described below, among other things, the mass diffusion rate of the evaporated liquid and the drying time were calculated. The calculation was made under the following assumptions: $$H=300\mathrm{microns}.\mathit{H}=10\mathrm{microns}.{\delta }_G=300\mathrm{microns}$$

$$f=0.2.{\mathit{T}}_G=350K.{\mathit{T}}_H=295K$$

$$\begin{array}{cc}{\lambda }_L& =0.6W\left(\mathrm{mK}\right),{\rho }_L=1000\mathrm{kg}/{\mathrm{m}}^3,{\Delta h}_{\mathit{LH}}=2260\mathrm{KJ}/\mathrm{Kg}\\ {\lambda }_S& =0.12W/\left(\mathrm{mK}\right)\hfill \end{array}$$

The following material properties were assumed to be constant, despite the temperature changes: $${\mu }_G=1.8\times {10}^{-5}\mathrm{kg}/\left(\mathrm{ms}\right).{\lambda }_G=0024W/\left(\mathrm{mK}\right).{\mathit{C}}_P=1012\mathrm{KJ}/\left(\mathrm{KgK}\right)$$

$$\begin{array}{cc}{\lambda }_L& =0.6W\left(\mathrm{mK}\right).{\rho }_L=1000\mathrm{kg}/{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="imgf0005.png"\; state="\{\{state\}\}">m</figure-callout>}}^3.{\Delta H}_{\mathit{LH}}=2260\mathrm{KJ}/\mathrm{kg}\\ {\lambda }_S& =\mathrm{12:12}W/\left(\mathrm{mK}\right)\hfill \end{array}$$

The drying of the fluid film according to the invention is essentially determined by checking the second temperature T _H on the transport surface and by the first temperature T _{G of} the heat source. The heat source is disposed at a distance δ _G from the side facing the gas phase boundary surface of the fluid film.

Fig. 2 shows the interface temperature T _I over the first temperature T _{G of} the heat source or gas phase. Fig. 3 show the Interface temperature T ₁ above the temperature T _{H of} the transport surface.

As in particular from the Fig. 3 to 5 can be seen, the mass diffusion rate can be achieved by increasing the first temperature T _G. It can also be seen that an increase in the second temperature T _H causes a reduction in the mass diffusion rate.

As in particular from the 6 and 7 can be seen, a reduction of the drying time can be achieved if the second temperature T _H small and the first temperature T _{G is selected} high. Both temperatures T _G and T _H are adjustable so that T _I can be controlled. T _I can z. B. be kept at room temperature.

Fig. 8 shows a schematic sectional view of an embodiment of a diffusion dryer according to the invention. In a housing 1 is a supply roller 2, on which the substrate 3 to be coated is received. The substrate 3 is guided over first tension rollers 4a, 4b on a transport roller 5. A jacket or transport surface 6 of the transport roller 5 is partially surrounded by a drying device 7, preferably over an angle of 180-270 °. Upstream of the drying device 7, a slot nozzle tool designated by the reference numeral 8 is provided for applying a fluid film F to the substrate 3. Downstream of the drying device 7 is at least one further tension roller 9, via which the substrate 3 is wound onto a roller 10. Reference numeral 11 denotes a roller cleaning device which is downstream the drying device 7 and upstream of the coating tool 8 is arranged.

The drying device 7 has a further housing 12. The further housing 12 is provided with suction devices 14, with which a liquid vapor escaping from the fluid film F is extracted.

As in particular in conjunction with Fig. 9 can be seen, a recorded in the other housing 12 heat source 13 may be formed, for example, of resistance heating wires, which are arranged like a grid. The heating wires form a heating surface G, which is arranged at a distance δ _G of, for example, 0.1 mm to 1.0 mm opposite the interface I of the fluid film F. By the in Fig. 9 Absauginrichtungen not shown in detail 14 results in a substantially perpendicular to the transport surface 6 forming flow, which in Fig. 9 indicated by arrows. By the suction means 14, a negative pressure in the space between the interface I and the heating surface G is advantageously generated. This avoids the escape of any combustible liquid vapors into the environment. The housing 1 can also be flushed with a protective gas atmosphere in order to avoid a risk of fire or explosion due to the escape of the combustible liquid vapors.

In the Fig. 8 shown inventive device is particularly compact. Instead of a transport roller 5, a plurality of transport rollers 5 can be used. Thus, a drying section can be increased, which allows drying of relatively thick fluid films F. Furthermore, the device according to the invention can also be used in combination with conventional convection dryers. To this Purpose of the device according to the invention is advantageously used upstream of a conventional convection dryer. By using the device according to the invention in combination with a conventional convection dryer, the energy used to operate the conventional convection dryer can be drastically reduced.

At the in Fig. 10 shown schematic sectional view through a further embodiment of a diffusion dryer according to the invention or a further drying device 15 shown. In this case, the substrate 3 is in turn received on a supply roll 2; it is transported by a driven roller 16. The reference numeral 8 again denotes a slot nozzle tool for applying a fluid film to the substrate 3, which is arranged upstream of a further drying device 15.

The further drying device 15 comprises in the transport direction T heating elements 17, which may be arranged in the transport direction T successively arranged plate-shaped resistance heating. In this embodiment, the heating elements 17 form a substantially closed heating surface G, which is arranged at a distance δ _G of 2 to 10 mm from a substrate surface. The further drying device 15 thus has a rectangular channel K with the height δ _G , through which the substrate 3 is guided in the transport direction T.

By means of the suction device 14, air L is sucked into the channel K at the upstream end of the further drying device 15 and moved counter to the transport direction T in the direction of the suction device 14 in countercurrent. It is a flow rate, for example, 30 cm / s to 3 m / s.

Another transport surface 18 of the further drying device 15 is formed here just. It can also be designed to be heatable (not shown here).

LIST OF REFERENCE NUMBERS

1

casing

2

supply roll

3

substratum

4a, 4b

idler

5

transport roller

6

transport surface

7

drying device

8th

Slot nozzle tool

9

further tensioning roller

10

roller

11

Roller cleaning device

12

further housing

13

heat source

14

suction

15

further drying device

16

driven roller

17

heating element

18

additional transport area

δ _G

distance

F

fluid film

G

heating surface

I

interface

L

air

T

transport direction

Claims (25)

1. A method for drying a fluid film (F), which is applied to a surface of a substrate (3) and includes a vaporizable liquid, comprising the following steps:

   transporting the substrate (3) on a transport surface (6) of a transport device (5) along a transport direction (T) through a drying device (7);

   vaporizing the liquid by way of a heat source (13) having a heating surface (G), wherein the heating surface (G) is disposed at a distance (δ_G) of 0.1 mm to 15.0 mm opposite the substrate surface; and

   removing the vaporized liquid in the direction of the heat source (13)

   characterized in that

   the heat is essentially transmitted from the heating surface (G) to the fluid film (F) by way of direct heat conduction.
2. The method according to claim 1, wherein a first temperature T_G of the heating surface (G) is controlled as a function of an interface temperature T_I of the fluid film (F) .
3. A method according to any one of the preceding claims, wherein the first temperature T_G is controlled in the range of 50ºC to 3005ºC, and preferably in the range of 80ºC to 200ºC.
4. A method according to any one of the preceding claims, wherein the transport surface (6) is heated by way of an additional heat source.
5. A method according to claim 4, wherein a second temperature T_H of the transport surface (6) generated by the additional heat source is controlled as a function of the interface temperature T_I.
6. A method according to claim 5, wherein the second temperature T_H is controlled so that the following relationship is met: $${\mathrm{T}}_{\mathrm{H}}={\mathrm{T}}_{\mathrm{I}}+\mathrm{\Delta T},$$

   

   where

   T_I ranges from 5°C to 40°C and

   ΔT ranges from 2 to 30°C, and preferably from 5 to 10°C.
7. A method according to any one of the preceding claims, wherein the vaporization of the liquid is carried out in a non-flammable gas atmosphere, and preferably a nitrogen or carbon dioxide atmosphere.
8. A method according to any one of the preceding claims, wherein the heating surface (G) facing the substrate (3) is disposed at a distance (δ_G) of 0.2 mm to 5.0 mm opposite the substrate surface.
9. A method according to claim 5 or 6, if depending on claim 2, or according to claim 7 or 8, if depending on claims 2 and 5, wherein the second temperature T_H is controlled so as to always be lower than the first temperature T_G.
10. A method according to claim 5 or 6, if depending on claim 2, or according to claim 7 or 8, if depending on claims 2 and 5, or according to claim 9, wherein a temperature difference between the first temperature T_G and the second temperature T_H is controlled so that a predetermined temperature difference profile develops along the transport device (5).
11. A method according to any one of the preceding claims, wherein a heat source through which a flow is possible is used as the heat source (13) and the vaporized liquid is removed through the heat source (13).
12. A method according to any one of the preceding claims, wherein the heat source (13) used is an electrical heating source.
13. A method according to any one of the preceding claims, wherein the heat source (13) used is a heat exchanger.
14. A method according to any one of the preceding claims, wherein the transport device used is at least one rotatable roller (5), the lateral face of which forms the transport surface (6).
15. A device for drying a fluid film (F), which is applied to a surface of a substrate (3) and includes a vaporizable liquid, comprising:

    a transport device (5) for transporting the substrate (3) on a transport surface (6) along a transport direction (T);

    a heat source (13) that is provided opposite the substrate (3) and has a heating surface (G), which is disposed at a distance (Δ_G) of 0.1 to 15.0 mm opposite the substrate surface; and

    a device (14) for removing the vaporized liquid (F) in the direction of the heat source (13),

    characterized in that

    the heat is essentially transmitted from the heating surface (G) to the fluid film (F) by way of direct heat conduction.
16. The device according to claim 15, wherein an additional heat source is provided for heating the transport surface (6) .
17. The device according to either claim 15 or 16, wherein a first controlling device is provided for controlling a first temperature T_G generated by the heating surface (G) as a function of an interface temperature T_I of the fluid film (F).
18. A device according to any one of claims 15 to 17,
    wherein a second controlling device for controlling a second temperature T_H of the transport surface (6) is provided as a function of the interface temperature T_I.
19. A device according to any one of claims 17 to 18,
    wherein a temperature difference between the first temperature T_G and the second temperature T_H is controlled by way of the first and/or second controlling devices so that a predetermined temperature difference profile develops along the transport direction (T).
20. A device according to any one of claims 15 to 19,
    wherein a device for rinsing a housing (1) surrounding the transport device (5) with a non-flammable gas, preferably a nitrogen or carbon dioxide atmosphere, is provided.
21. A device according to any one of claims 15 to 20,
    wherein the heating surface (G) facing the substrate (3) is disposed at a distance (δ_G) of 0.2 mm to 5.0 mm opposite the substrate surface.
22. A device according to any one of claims 15 to 21,
    wherein a heat source through which a flow is possible is used as the heat source (13) so that the vaporized liquid can be removed through the heat source (13).
23. A device according to any one of claims 15 to 22,
    wherein the heat source (13) is an electrical heating source.
24. A device according to any one of claims 15 to 23, wherein the heat source (13) is a heat exchanger.
25. A device according to any one of claims 15 to 24,
    wherein the transport device comprises a rotatable roller (5), the lateral face of which forms the transport surface (6) .

Images