EP1158836B1 - Radiation arrangement and its use and the treatment process of upper surfaces - Google Patents

Description

The invention relates to a radiation arrangement with at least one infrared radiator and at least one further radiator with at least two interconnected elongated, permeable to light and IR radiation and sealed with respect to the ambient atmosphere, envelope tubes, of which at least a first envelope tube an incandescent filament which is electrically connected via sealed pipe ends and external contacts to an external power supply, as well as their use and a method for the treatment of surfaces.

From GB-PS 15 44 551 an electric heat radiator is known, which has two mutually parallel helical heating coil, which are each arranged in a quartz glass tube, wherein the quartz glass tubes are in their length by a fusion connection with each other. The two filaments are connected in series.

Even if a considerable increase in intensity can be achieved, only a relatively narrow spectral range of short-wave infrared radiation is output, it being difficult at the same time colors or pigments and their solution, for example water, after a surface application, such as printing on a Carrier to dry quickly.

Furthermore, EP 0 428 835 A2 and corresponding US Pat. No. 5,091,632 also disclose infrared radiators with twin tube radiators.

Furthermore, it is known from DE 198 39 457 A1 to use an infrared radiator with a carbon ribbon as a heating element; Such a carbon ribbon is particularly suitable for emitting IR radiation in a mean wavelength range of 1.5 to 4.5 microns.

The invention has as its object to provide a thermal radiation arrangement to rapidly dry on surfaces applied coatings or imprints with pigments or paints in solvents and at the same time to let the solvents such as toluene or water evaporate quickly.

The object is achieved according to the device in that at least a second sheath tube is provided, which has a radiator belt, which is also electrically connected via sealed ends and external contacts with or with another external power supply. The second cladding tube is likewise provided for emitting infrared radiation, in particular for emitting IR radiation in the middle IR range. Of course, a different temperature radiator instead of the radiator band can be used, which emits radiation in the central IR range. It proves to be advantageous that the arrangement has relatively high radiation components both in the visible spectral range and in the near infrared radiation range, in particular with a wavelength in the range of 780 nm to 1.4 μm, as well as in the central IR radiation range, in particular with a wavelength in the range from 2.5 μm to 5 μm.

In a preferred embodiment of the device, an elongated carbon band is used as the radiator band, wherein the carbon band is formed in a further preferred form as an elongated spiral. It emits radiation in a medium IR spectral range, while an incandescent filament emits short-wave IR radiation (near IR) and optionally also visible light.

It proves to be particularly advantageous that by combining radiation sources with different temperatures (Δλmax> 400 nm) in a common radiation arrangement, the efficiency of heat treatment processes can be increased over conventional short-wave IR radiation sources. For example, the efficiency of paint drying processes is improved.

By virtue of its superimposition of different Planck distributions, the radiation arrangement has a percentage of more IR radiation components than previous radiation sources with only one temperature in the specified wavelength ranges.

In a further advantageous embodiment, it is possible to provide at least one additional, permeable to light and UV radiation, elongated tube in addition to thermal radiation sources, which has an electrical discharge path and a emits additional UV radiation in the wavelength range of 0.15 to 380 nm, which is particularly suitable for color drying.

Preferred embodiments of the infrared radiator or the radiation arrangement are specified in claims 1 to 13.

Particularly advantageous is the reduced space requirement compared to individual radiators, whereby optimal radiation conditions can be set by selectively operating the radiation sources with different wavelengths for the respective fields of application.

A use of the object according to the invention is provided by using a twin-tube radiation arrangement with incandescent filament as the short-wave infrared radiator source and a tube provided with carbon ribbon as a radiator band as medium-wave IR radiator.

The object is achieved in a method for the treatment of surfaces by IR irradiation, in particular of coated or printed surfaces on substrates or dissolved color pigments on a support for drying is irradiated, achieved in that the surface at least temporarily with an IR radiation with a high proportion in a first wavelength range of 780 nm to 1.2 microns and at least temporarily treated simultaneously with an IR irradiation with a high radiation component in a second wavelength range of 2.5 microns to 5 microns.

Advantageous embodiments of the method are given in claims 17 and 18.

In a preferred embodiment of the method, the surface irradiation of the first wavelength range and the second wavelength range overlap at least temporarily, wherein the first IR radiation is emitted from a radiator with a filament and the second IR radiation from a radiator with a carbon band as the radiation source. It proves to be particularly advantageous that, when the first and second wavelength ranges are superimposed, a spectral radiation distribution is achieved with a relatively high radiation fraction in the wavelength range from 780 nm to 3.1 μm.

A significant advantage is the fact that, depending on the embodiment, the individual radiation components of this radiation arrangement can be switched in an OR operation or operated in a common Schaltart. This results in the operation of machines with changing processes, the advantage that no spot change must take place. Also, the user no longer needs different individual sources of radiation so that a reduction in spare parts inventory is achieved.
In addition, the carbon emitter used can be used as a starting current limiter for the short-wave radiator (incandescent filament).

In a further embodiment, UV radiation components can also be superimposed with the IR spectra. Again, separate and common modes can be combined.

In the following, the object is explained in more detail with reference to the figures 1a, 1b, 1c, 2, 3 and 4. FIG. 1a schematically shows a perspective view of a twin tube emitter according to the invention.

Figure 1b shows a front view of a twin tube radiator, but having a coiled carbon radiator.

Figure 1c shows a frontal view of an arrangement which additionally has a tubular discharge lamp, so that in addition to infrared radiation and UV radiation can be generated.

FIG. 2 shows in the diagram the relative intensity of a Planck spectral radiation distribution with KW / m ² nomination with a short-wave infrared radiator (NIR / IR-A) at an operating temperature of 2600 ° C. and a carbon radiator at an operating temperature of approximately 950 ° C. , wherein the intensity is plotted against the wavelength lambda [μm].

FIG. 3 shows in the diagram the spectral absorption of the water for different layer thicknesses (2 μm, 10 μm), wherein the absorption in the range from 0 to 100 percent is plotted against the lambda wavelength in μm.

Figure 4 shows in the diagram the efficiency of water drying for a layer of 10 microns thickness, wherein the temperature is plotted in Kelvin along the X-axis, while the efficiency along the Y-axis is entered.

According to FIG. 1 a, the radiation arrangement has a twin tube emitter 1, which contains two enveloping tubes 2, 3 made of infrared transparent and visible radiation, preferably quartz glass, at least approximately parallel to one another, the two tubes being formed by an intermediate web 4, which is likewise made of Quartz glass exists, mechanically firmly connected to each other. The first tube 2 has a shortwave infrared radiator provided with an incandescent filament 5, the high emission intensity of which lies in the wavelength range from 780 nm to approximately 1.2 μm (near IR / IR-A), as shown in the following FIG. 2 (curve II). evident. The definition of the wavelength range results from DIN standard 5030, part 2.

A similar radiator is known for example from the aforementioned EP 0 428 835 or the corresponding US 5,091,632. In such a short-wave infrared radiator is according to Figure 1a, the filament 5 of the sheath tube 2 via sheet-shaped current feedthroughs 6, 7 of molybdenum in the respective pinch region of the pipe ends 8 ', 9' of the tube 2, each with an external terminal contact 8, 9 electrically and mechanically connected which is for electrical connection to an external power supply. On the other hand, the tube 3 has an infrared radiator with a carbon ribbon as the radiator band 10 which is provided with terminal contacts 11, 12 and sheet-shaped current feedthroughs 13, 14 of molybdenum in the respective pinch region of the tube ends 15, 16 for connection to the power supply ,

The connection between the ends of the carbon strip 11 and the current feedthroughs 13, 14 preferably takes place via graphite paper, as is known, for example, from DE 44 19 285 C2 or the corresponding US Pat. No. 5,567,951. In this way, the pronounced in the longitudinal direction of the electrical conductivity of the carbon ribbon to be compensated when contacting the current implementation. In addition, an improvement of the cooling is achieved.

The frontal view of Figure 1b shows the two adjacent sheaths 2 and 3 of the twin tube radiator 1, which are connected to each other via a gutter 4 made of quartz glass. In contrast to FIG. 1a, in which an elongated flat emitter strip 10 is shown, emitter strip 10 'according to FIG. 1b is wound prior to introduction into the carbon emitter, ie a helical spiral serves as emitter strip 10'. The coiled radiator strip 10 'has the particular advantage that a greater proportion of radiation in the wavelength range of 1.6 to 3.8 microns (near IR / IR-B to average IR / IR-C) according to curve 1 of Figure 2 are emitted can, as it results from the Stefan Boltzmann's law. The definition of the wavelength range results from DIN standard 5030, part 2.

The cladding tubes 2 and 3 are - as already explained with reference to Figure 1a - mechanically connected to each other via a gutter 4. The terminal contacts 8, 9, 17 '17 "and 18', 18" correspond in their function largely to the illustrated with reference to Figure 1 contacts 17, 18. Due to the separately led out terminal contacts a single control of the respective lamps is possible, so this example can be operated simultaneously or alternately in time.

The frontal view of a radiator combination shown in FIG. 1c has, in addition to the previously described twin arrangement, an additional radiator arrangement connected as a discharge lamp, wherein the quartz glass envelope tube 19 of quartz glass of the discharge lamp additionally connected via an intermediate web 4 '(quartz glass) enables the emission of UV radiation. Since the discharge lamp 20 is connected via the intermediate web 4 'to the twin-tube radiator arrangement 1', it is also possible here to speak of a triple-tube radiator arrangement. It is thus possible to treat color pigments by visible light and infrared radiation, and at the same time or alternately to treat photoinitiators by means of UV irradiation by discharge lamp 20. The filling of the discharge lamp 20 is preferably made of mercury and possibly an admixture of metal halides, wherein the electrodes 21, 22 are preferably made of tungsten. The power supply of discharge lamp 20 via current feedthroughs, 23, 24, which are preferably formed as molybdenum foils. The additional cladding tube 19 of the discharge lamp 20, like the web 4 'or web 4, consists of quartz glass, so that optimal transparency for UV radiation is provided here. The connection contacts 26, 27 of the discharge lamp 20 are also led out separately, so that the discharge lamp 20 can be ignited and operated independently of the other two infrared radiators.

Thus, it is possible to provide a compact universally applicable radiator arrangement, which on the one hand stored and stored space-saving, on the other hand can be used in a variety of different functions.

As can be seen from the diagram shown in FIG. 2, the relative intensity maximum of a carbon emitter having a temperature of 950 ° C. (curve I) is in the range from 1.6 to 3.8 μm. With a simultaneous operation of incandescent filament 5 (curve II) and carbon ribbon 10 or 10 'as emitters, a combination of both emitters produces a thermal radiation source which has a high total radiation fraction in the range from 780 nm to 3.5 μm according to curve III ( near IR to the beginning of middle IR). Such a combination increases the efficiency of processes where both color pigments must be dried and associated solvents such as toluene or water, which should be removed from paints, or paints by evaporation. Thus, short reaction times and high power densities of the short-wave infrared radiation sources can be achieved by the double radiator according to the invention.
With an increase in the temperature of the carbon ribbon 10 or 10 'to 1200 ° C., a similar spectral radiation distribution of the intensity can be achieved, as has already been illustrated with reference to FIG.

FIG. 3 shows the spectral absorption of the water on the basis of the diagram, with a first maximum spectral absorption, both for a larger layer thickness of, for example, 10 μm (curve I) and for a smaller layer thickness of 2 μm (curve II) of the applied layer with A1, A1 ', occurs in the wavelength range of about 3 microns, while a second lower maximum with absorbance of about 40 to 90 percent in a designated A2, A2' spectral range of about 6 microns. It can be seen that a layer thickness of only 2 microns has a lower degree of absorption in the absorption points A1 'and A2' of the curve II, each with 90 percent and 40 percent.

It can be seen from FIG. 3 that the maximum of the radiation required for the evaporation of water or other solvents is more in the mid-infrared range (IR-C / MIR according to DIN 5030, Part 2), whereas drying of the color pigments according to FIG already successfully carried out in the short-wave range from 780 nm to about 1.2 μm (NIR / IR-A according to DIN 5030, 2nd part).

According to Figure 4, the efficiency of water drying for a layer of 10 microns thickness in a functional relationship with the temperature; at a temperature in the range of 1500 to 1200 K, the efficiency is in the range of 30 to 40 percent, while falling in the range of 3000 K and above below 10 percent. It can thus be seen that optimum water drying efficiency in the range of 1000 to 1500 K can be achieved.

On the basis of the figures 2 to 4 is thus seen that due to the simultaneous action of the short-wave infrared radiation by incandescent in cooperation with the medium-wave infrared radiation by carbon tape very different requirements for drying and evaporation of applied layers or imprints are met, so that by this type of Combination a synergy effect occurs.

Claims (18)

1. Radiation arrangement with an infrared radiator and a further radiator with at least two elongated envelope tubes (2), permeable to light and IR radiation, joined together and closed off from the ambient atmosphere, of which at least a first envelope tube has an incandescent coil (5), which is electrically connected via sealed tube ends (8', 9') and outer contacts (8, 9) to an external power supply, characterised in that a second envelope tube (3) is provided, which has a radiating strip (10, 10'), which is also electrically connected via sealed ends (15, 16), and outer contacts (17, 18) to the external power supply.
2. Radiation arrangement according to claim 1, characterised in that an elongated carbon strip is used as the radiating strip (10).
3. Radiation arrangement according to claim 1 or 2, characterised in that the radiating strip (10') is configured as an elongated coil.
4. Radiation arrangement according to any one of claims 1 to 3, characterised in that at least one additional elongated envelope tube (19) permeable to light and UV radiation, is joined to both envelope tubes (2, 3), the additional tube (19) having an electrical discharge gap.
5. Radiation arrangement according to claim 4, characterised in that the additional tube (19) having the discharge gap has opposing electrodes (21, 22), which can be connected in each case to an external power supply via sealed tube ends with a current lead-through and terminal contacts (26, 27).
6. Radiation arrangement according to claim 4, characterised in that electromagnetic energy is injected into the tube interior to excite the discharge in the additional tube (19).
7. Radiation arrangement according to claim 6, characterised in that the electromagnetic energy is injected via electrodes located outside the tube interior.
8. Radiation arrangement according to any one of claims 4 to 7, characterised in that electrodes for the operation of the discharge gap are connected to a power supply via external contacts.
9. Radiation arrangement according to any one of claims 1 to 8, characterised in that the external contacts are electrically connected individually in each case to terminals of a joint power supply.
10. Radiation arrangement according to any one of claims 1 to 9, characterised in that at least one of the tubes has a reflective coating.
11. Radiation arrangement according to any one of claims 1 to 10, characterised in that the direction of the emission of radiation from the tubes (2, 3) is oriented at least approximately parallel.
12. Radiation arrangement according to any one of claims 1 to 11, characterised in that the direction of the emission of radiation is oriented toward a field to be irradiated jointly.
13. Radiation arrangement according to any one of claims 1 to 12, characterised in that at least two radiators can be electrically connected in series.
14. Use of the radiation arrangement according to any one of claims 1 to 13, wherein the envelope tube provided with the incandescent coil (5) is used as the IR radiation source in the near IR range and the envelope tube provided with the radiating strip (10, 10') is used as the IR radiation source in the near radiation range (IR-B) and medium IR range.
15. Use of the radiation arrangement according to any one of claims 4 to 13, wherein an additional envelope tube provided with a discharge space is used as the UV radiation source.
16. Method for the treatment of surfaces by means of IR radiation generated by a radiation arrangement according to any one of claims 1 to 13, in particular of coated surfaces on substrates or of dissolved paint pigments on a carrier for the purpose of drying, wherein the surface is irradiated from at least one infrared source for a predetermined time period, characterised in that the surface is treated at least intermittently with IR radiation in a first wavelength range of 780 nm to 1.4 µm and at least intermittently with an IR irradiation in a second wavelength range of 2.5 µm to 5 µm.
17. Method according to claim 16, characterised in that the irradiation of the first and second wavelength range at least intermittently overlaps.
18. Method according to claim 16 or 17, characterised in that the radiation of the first wavelength range is emitted from an IR radiator with an incandescent coil as the radiation source and the IR radiation of the second wavelength range is emitted from an IR radiator with a carbon strip as the radiation source.

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