EP1775997A2 - Radiation assembly and its use and it method for treating upper surfaces - Google Patents

Abstract

Method for treating a surface with IR radiation comprises treating the surface with IR radiation in a first wavelength of 780 nm to 1.4 mu m and temporarily with IR radiation in a second wavelength of 2.5 to 5 mu m. An independent claim is also included for a device for treating a surface with IR radiation comprising an encased tube provided with a spiral-wound filament (5) as IR source in the near IR region and an encased tube provided with a radiating strip (10) as IR source in the near-to-middle IR region. Preferred Features: The radiation of the first and second wavelength regions temporarily overlap.

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 against the ambient atmosphere cladding tubes, of which at least a first cladding tube has a filament, the sealed pipe ends and external contacts is electrically connected to an external power supply, as well as their use and a method for the treatment of surfaces.

From the GB-PS 15 44 551 For example, an electric heat radiator is known which has two helical heating coils arranged parallel to one another, each arranged in a quartz glass tube, the quartz glass tubes being in their length by a fusion connection with one another. The two filaments are connected in series.

Even if a considerable increase in intensity can be achieved, only a relatively narrow spectral range of the 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, from the EP 0 428 835 A2 or the corresponding US 5,091,632 Also known as infrared emitters with twin tube emitters.

Furthermore, it is from the DE 198 39 457 A1 known 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 quickly 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 one second cladding tube is provided which has a radiator band, which is also electrically connected via sealed ends and external contacts to 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 infra-red radiation range, in particular with a wavelength in the range from 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 ribbon is used as the radiator band, wherein the carbon ribbon 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 (Δλ max> 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, in addition to thermal radiation sources, to provide at least one additional, elongated tube permeable to light and UV radiation, which has an electrical discharge path and outputs additional UV radiation in the wavelength range from 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 4.

Particularly advantageous is the reduced space requirement compared to individual radiators, wherein optimum 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 the radiator band as the 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 2 and 3.

In a preferred embodiment of the method, the surface irradiation of the first wavelength range and of the second wavelength range overlap at least temporarily, wherein the first IR radiation from a radiator with a filament and the second IR radiation emitted 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 advantage of the operation of machines with changing processes 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 emitter (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.

The object is explained in more detail below with reference to FIGS. 1 a, 1 b, 1 c, 2, 3 and 4. FIG. 1 a shows a perspective view of a twin tube radiator according to the invention,

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

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

Figure 2 shows in the diagram the relative intensity of a spectral radiation distribution Planck 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 about 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 mutually at least approximately parallel sheaths 2, 3 made of transparent material for infrared radiation and visible radiation, preferably quartz glass, wherein the two tubes by a gutter 4, which also consists of quartz glass , are mechanically fixed together. 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). The definition of the wavelength range results from DIN standard 5030, part 2.

A similar radiator is for example from the aforementioned EP 0 428 835 or the corresponding US 5,091,632 known. In such a short-wave infrared radiator according to Figure 1a, the filament 5 of the cladding 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, the for electrical connection to an external power supply. On the other hand, the tube 3 has an infrared radiator with a carbon ribbon as a radiator band 10, which is provided with external terminal contacts 17, 18 for connection to the power supply via terminal contacts 11, 12 and sheet-shaped current feedthroughs 13, 14 made of molybdenum in the respective pinch region of the pipe ends 15, 16 ,

The connection between the ends of the carbon ribbon 11 and the current feedthroughs 13, 14 is preferably carried out over graphite paper, as for example from the DE 4419 285 C2 or the corresponding US 6,567,951 is known. In this way, the pronounced in the longitudinal direction of 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 radiator strip 10 is shown, the radiator belt 10 'according to FIG. 1b is wound prior to introduction into the carbon radiator, i. that a helical coil serves as a radiator band 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) are emitted according to curve I of Figure 2 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 1 a - mechanically connected to each other via a gutter 4; the connection contacts 8, 9, 17 ', 17 "and 18', 18" correspond in their function largely to the contacts 17, 18 explained with reference to FIG.

Due to the separately led out terminal contacts a single control of the respective lamps is possible, so that they can be operated, for example, simultaneously or temporally alternating,

The frontal view of a radiator combination shown in FIG. 1 c has, in addition to the twin arrangement described above, 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) makes it possible to emit UV radiation. Since the discharge lamp 20 is connected via gutter 4 'with the Zwülingsrohrstrahleranordnung 1', can also be spoken of a triplet tube radiator arrangement, It is thus possible to treat by visible light and infrared radiation color pigments and simultaneously or alternately photo-initiators by means of UV Irradiation by the discharge lamp 20 to treat. 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 energy 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 web 4 'or web 4, consists of quartz glass, so that optimum transparency for UV radiation is provided here. The connection contacts 26, 27 of the discharge lamp 20 are likewise 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 radiator 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 in which both color pigments must be dried, as well as associated solvents such as toluene or water to 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 1) 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 ribbon 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 (4)

Process for the treatment of surfaces by means of IR radiation, in particular of coated surfaces on substrates or of dissolved color pigments on a support for drying, wherein the surface is irradiated for a predetermined period of time from at least one infrared source, characterized in that the surface at least temporarily with a IR radiation in a first wavelength range of 780 nm to 1.4 microns and at least temporarily treated with an IR radiation in a second wavelength range of 2.5 microns to 5 microns. A method according to claim 1, characterized in that the irradiation of the first and the second wavelength range at least temporarily superimposed. A method according to claim 1 or 2, characterized in that the radiation of the first wavelength range is emitted from an IR radiator with a filament as the radiation source and the IR radiation of the second wavelength range from an IR radiator with a carbon band as the radiation source. Use of a radiation order, characterized in that a cladding tube provided with an incandescent filament (5) as an IR radiation source in the near IR region and a cladding tube provided with a radiator band (10, 10 ') as IR radiation source in the near IR region (IR -B) and middle IR range is used.

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