EP1791652A2

EP1791652A2 - Device and process for curing using energy-rich radiation in an inert gas atmosphere

Info

Publication number: EP1791652A2
Application number: EP05753770A
Authority: EP
Inventors: Andreas Daiss; Erich Beck; Manfred Biehler
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2004-06-24
Filing date: 2005-06-17
Publication date: 2007-06-06
Anticipated expiration: 2025-06-17
Also published as: JP4819803B2; ES2346068T3; DE502005009765D1; US7863583B2; KR20070034073A; JP2008503338A; EP1791652B1; ATE471218T1; US20080311309A1; CN101304814B; WO2006000349A3; WO2006000349A2; DE102004030674A1; BRPI0512542A; CN101304814A

Abstract

The invention relates to an apparatus and a method of producing molding materials and coatings on substrates by curing radiation-curable materials under an inert gas atmosphere by exposure to high-energy radiation.

Description

Apparatus and method for curing with high-energy radiation under inert gas atmosphere

description

The invention relates to a device and a method for the production of molding compounds and coatings on substrates by curing radiation-curable compositions under an inert gas atmosphere by irradiation with high-energy radiation.

In the radiation curing of radically polymerizable compounds, e.g. Of (meth) acrylate compounds or vinyl ether compounds, a strong inhibition of polymerization or curing by oxygen may occur. This inhibition results in incomplete surface hardening, e.g. to sticky Beschich¬ lines.

This oxygen inhibition effect can be achieved by the use of high amounts of photoinitiator, by co-using coinitiators, for. Amines, high energy, high dose UV radiation, e.g. be reduced with high pressure mercury lamps or by the addition of barrier-forming waxes.

It is also known to carry out the radiation curing under an inert protective gas, e.g. from EP-A-540884, from Joachim Jung, RadTech Europe 99, Berlin 08. to 10.11.1999 in Berlin (UV Applications in Europe Yesterday-Today Tomorrow).

Radiation-curable compositions may contain both volatile diluents, such as, for example, water or organic solvents, and be processed in the absence of such diluents. The process of radiation curing is suitable for coatings which are carried out in industrial applications or in medium or small craft enterprises or in the domestic sector. So far, however, has the complicated implementation of the method and the benö¬ ended devices, in particular the UV lamps, an application of radiation curing in the non-industrial areas prevented.

WO 01/39897 describes a process for radiation curing under an inert gas atmosphere which is heavier than air, preferably carbon dioxide. A preferred embodiment for curing described therein takes place in a dip tank.

There is a need to improve the method disclosed therein by further reducing protective gas losses and the contamination by atmospheric oxygen, which occur, for example, when the protective gas atmosphere is heated, for example caused by the waste heat. Desired is a greater independence of heat sources in the irradiation room and thus to achieve more freedom with the choice of type, positioning and number of irradiation options. In RadTech Conference Proceedings, November 3 - 5, 2003, Berlin, Germany, Dr. Ing. Eicheck Beck, BASF AG, Germany; "UV Curing under Carbon Dioxide", p. 855-863; Volume II, ISBN 3-87870-152-7, discloses methods and a device for radiation curing under CO ₂ , which permits a continuous process for curing under inert gas. The disadvantage of this is that the consumption of inert gas is still relatively high.

The object of the invention was to provide a device with which a radiation curing can be performed and you can keep the consumption of inert gas as low as possible.

The object has been achieved by a device 1 for carrying out a curing of coatings on a substrate S under an inert gas atmosphere containing

Side covers 2, 3, 4 and 5, upper and lower covers 6 and 7, wherein 2, 3, 4, 5, 6 and 7 together enclose an inner space, one or more partitions 8, which divide the interior, wherein the partitions. 8 terminate with the lower cover 7 and leave a distance dϊ to the upper cover 6, one or more partition walls 9, which divide the interior, the partitions 9 terminate with the upper cover 6 and leave a distance d2 to the lower cover 7, - 8 and 9 with the respectively adjacent dividing wall 9 or 8 and, if appropriate, the lateral covers 2 or 3 form a subdivided interior space (compartment), at least one radiation source 10 radiating within the interior and / or into the interior space, - at least one gas supply device 11, with which a gas or Gasge¬ mixture can be guided or formed in the interior, at least one conveying device 12 for the substrate S, Einla 13 and outlet 14, - Wherein the partitions 8 hen standing substantially perpendicular to the lower cover 7, the partitions 9 are substantially perpendicular to the upper cover 6, the distances d1 and d2 and the width b of the device 1 are selected in that they are larger than the dimensions of the substrate S along the conveying direction of the conveying device 12 and by the devices 2, 3, 8 and 9 at least 4 compartments are formed.

Shielding gases which are heavier than air and those which are lighter than air can be used in the device according to the invention.

The molecular weight of an inert gas which is heavier than air is therefore greater than 28.8 g / mol (corresponds to the molecular weight of a gas mixture of 20% oxygen O ₂ and 80% nitrogen N ₂ ), preferably greater than 30 g / mol, particularly preferably min - at least 32 g / mol, in particular greater than 35 g / mol. Suitable examples include noble gases such as argon, hydrocarbons and halogenated hydrocarbons. Carbon dioxide is particularly preferred.

The supply of carbon dioxide may be from pressurized containers, filtered combustion gases, e.g. of natural gas or hydrocarbons, or preferably as dry ice er¬ follow. The supply of dry ice is considered to be advantageous, in particular for applications in the non-industrial or in the small industrial sector, since solid dry ice can be transported and stored as a solid in simple containers insulated with foams. The dry ice can be used as such, it is then in gaseous form at the usual temperatures of use. Another advantage in the use of dry ice is the cooling effect that can be used for the condensation and removal of volatile coating components, such as solvents or water (see below).

Shielding gases which are lighter than air are those having a molecular weight of less than 28.8 g / mol, preferably not more than 28.5 g / mol, more preferably not more than 28.1 g / mol. Examples of these are molecular nitrogen, helium, neon, carbon monoxide, steam, methane or nitrogen-air mixtures (so-called lean air), particular preference is given to nitrogen, water vapor and nitrogen-air mixtures, very particular preference is given to nitrogen and nitrogen. Air mixtures, in particular nitrogen.

The supply of inert gases which are lighter than air can preferably be carried out from pressurized containers or from oxygen-depleted exhaust gases, for example from oxidations or coking exhaust gases or by separating off oxygen from gas mixtures, such as, for example, Air or combustion gases, over membranes.

The terms "protective gas" and "inert gas" are used interchangeably in this document and refer to those compounds which do not react significantly with the coating compositions when irradiated with high-energy radiation and which do not adversely affect their curing with respect to speed and / or quality. In particular, this is understood to mean a low oxygen content (see below). In it "does not mean Substantially react "that the inert gases under the applied in the process irradiation with high-energy radiation to less than 5 mol% per hour, preferably less than 2 mol% per hour and more preferably less than 1 mol% per hour with the coating materials or other substances within the device react.

The protective gas (mixture) is introduced into the device and the air is forced out of it.

The device now contains a protective gas atmosphere into which the substrate, which is coated with the radiation-curable composition, or the shaped body can be guided. Subsequently, the radiation hardening can take place.

During radiation curing, the average oxygen content (O ₂ ) in the protective gas atmosphere should be less than 15% by volume, preferably less than 10% by volume, more preferably less than 8% by volume, very preferably less than 6% by volume and in particular less than 3% by volume, based in each case on the total amount of gas in the protective gas atmosphere; With the method according to the invention, it is easy to set average oxygen contents below 2.5% by volume, preferably below 2.0% by volume and more preferably below 1.5% by volume. The particular difficulty is to be taken into account that three-dimensional substrates entrain oxygen into the device according to the invention (so-called scooping) and the oxygen content is therefore substantially more difficult to reduce than with two-dimensional objects such as films, webs or the like. In the guidance of two-dimensional substrates by the device according to the invention, lower oxygen contents than in the case of three-dimensional ones can also be achieved, for example up to less than 1% by volume, more preferably less than 0.5% by volume, particularly preferably less than 0.1% by volume %, very particularly preferably less than 0.05% by volume and in particular less than 0.01% by volume.

A protective gas atmosphere is understood to mean the gas volume during the irradiation with high-energy radiation, which surrounds the substrate at a distance of up to 10 cm from its surface.

Another advantage of curing in a protective gas atmosphere is that the distances between the lamps and the radiation-curable composition can be increased in relation to the curing in air. Overall, lower radiation doses can be used and a radiator unit can be used to cure larger areas.

In the case of the use of dry ice as a protective gas, for example, a feed of the device, which may be storage containers for dry ice at the same time, easily done. The monitoring of carbon dioxide consumption is directly determined by the consumption of dry ice solids. Dry ice sublimates at -78.5 ⁰ C directly to gaseous carbon dioxide. As a result, atmospheric oxygen is displaced upwards out of the basin in a basin without swirling.

The residual oxygen can be determined with commercially available atmospheric oxygen measuring devices. Because of the oxygen-reduced atmosphere in the device according to the invention and the risk of suffocation associated therewith, suitable safety measures should be taken. Likewise, sufficient ventilation and inert gas drainage should be ensured in adjacent work areas.

The device 1 according to the invention for carrying out a curing of coatings on a substrate S under an inert gas atmosphere contains

Side covers 2, 3, 4 and 5, upper and lower covers 6 and 7, wherein 2, 3, 4, 5, 6 and 7 together enclose an inner space, one or more partitions 8, which divide the interior, wherein the partitions. 8 with the lower cover 7 and leave a distance d1 to the upper cover 6, one or more partitions 9, which divide the interior, the partitions 9 complete with the upper cover 6 and leave a distance d2 to the lower cover 7, wherein 8 and 9 with the respectively adjacent dividing wall 9 or 8 and, if appropriate, the side covers 2 or 3 form a subdivided interior space (compartment), at least one radiation source 10 radiating inside the interior and / or into the interior, at least one gas supply device 11 with which a gas or gas mixture can be guided into the interior or formed there, - at least one conveying device 12 for the substrate S, - inlet ate 13 and outlet 14, wherein

the partitions 8 are substantially perpendicular to the lower cover 7, the dividing walls 9 are substantially perpendicular to the upper cover 6, the distances d1 and d2 and the width b of the device 1 are chosen to be greater than that Dimensions of the substrate S along the Förderrich¬ direction of the conveyor device 12 and - are formed by the devices 2, 3, 8 and 9 at least 4 compartments. An example of such a device is shown in FIGS. 1 to 4. The outer walls of the device according to the invention, namely front 2 and rear 3 covers, upper 6 and lower 7 covers and side covers 4 and 5, together enclose the interior of the device first

The partitions 8 and 9 of the device according to the invention in each case together with adjacent partitions 9 and 8 or with the front or hinte¬ ren cover 2 or 3 and with the side covers 4 and 5 and the upper and lower covers covers 6 and 7 compartments that divide the entire interior of the device. In this case, a compartment is formed by the walls enclosing it, which, if necessary, are designed to be extended over free spaces in order to close any gaps, for example in the case of partition walls 8, which extend to the conceptual design of a compartment up to the upper cover 6 be thought longer.

The number of compartments of the device according to the invention is at least 4, preferably at least 5 and more preferably at least 6. The number of compartments is not limited in principle, it is preferably up to 15, more preferably up to 12, most preferably up to 10 and in particular up to 8.

The partitions 8 and 9 are substantially perpendicular to the lower 7 and upper 6 cover. Essentially, this means that the angle α1, 8 and 7 or oc2, 9 and 6 enclose, not more than 30 ° from the vertical deviates, preferably not more than 20 °, more preferably not more than 15 °, especially not more than 10 °, in particular not more than 5 ° and especially not at all, wherein in the construction of the device according to the invention in general the usual structural error limits are taken into account.

Advantage of such a vertical promotion is that the device according to the invention saves space and occupies the least possible footprint. In addition, the device allows at the same time a simple shielding against UV radiation to the outside, so that radiation sources without filters, e.g. against UV-C radiation, can be used for efficient radiation utilization.

The partitions 8 and 9 are up to the described deviation from the vertical perpendicular to the front 2 and rear 3 covers, which in turn eben¬ may differ from the vertical.

All components of the device according to the invention are as far as ver¬ bound that as little inert gas escapes, except from the input 12 or the output 13, from the interior, ie any cracks, gaps, slots or holes are sealed. This also applies to the partitions, which, however, in the case of FIG. 8 need not be firmly connected to the lower cover 7 or, in the case of FIG. 9, to the upper cover 6 in order to possibly move the partitions. Here, between 8 and 7 or between 9 and 6, a narrow gap of preferably not more than 10 mm, particularly preferably not more than 7 mm, very particularly preferably not more than 5 mm, in particular not more than 3 mm, and especially not be more than 1 mm tolerable.

On the other hand, the dividing wall 8 with the upper cover 6 or the dividing wall 9 with the lower cover 7 leave enough space to convey the substrate through this intermediate space. The space between 8 and 6 leaves the space d1, the space between 9 and 7, the gap d2. The gaps d1 and d2 are designed so that they leave enough space for the dimensions of the substrate in the conveying direction of the conveyor 12.

Of course, for the entire path through the device according to the invention along the conveying device 12, sufficient space is left for the dimensions of the substrate in the conveying direction without the substrate touching other components and / or substrates.

In principle, the substrate can be conveyed in any desired orientation through the device according to the invention; preference is given to an orientation in which the flow resistance and the turbulence caused by the movement of the substrate are minimized. The cross-sectional area of the substrate projected in this direction in the conveying direction is assumed in this document to be the area of the substrate. The dimensions present in this orientation of the substrate, as conveyed by the device according to the invention, are used in this document as the characteristic dimensions of the substrate.

The substrate is preferably conveyed through the device according to the invention such that its projected cross-sectional area perpendicular to the conveying direction is as small as possible or at least not more than 25% more than this minimum, preferably not more than 20%, particularly preferably not more than 15%, especially preferably not more than 10% and in particular not more than 5%.

The cross-sectional area through which the substrate is conveyed through the individual compartments in the device according to the invention, ie the surface perpendicular to the conveying device 12 should in a preferred embodiment according to the invention amount to at least three times the projected cross-sectional area of the substrate in the conveying direction fourfold. In a further preferred embodiment according to the invention, the cross-sectional area should not be more than six times the area of the substrate, preferably not more than five times.

This cross-sectional area is, for example, the cross-sectional area Q1, which leaves the Trenn¬ walls 8 with the upper cover 6, so in the case of a square Öff¬ tion the surface d1 • b, or the cross-sectional area Q2, leaving the partitions 9 with the untren cover 7 that is, in the case of a square opening, the area d2 • b, or the cross-sectional area Q3 formed between the partitions and, if necessary, the walls 2 or 3, ie in the case of a square opening, the area d3 • b.

The height h of the device according to the invention should be at least twice the diameter d1 or d2, whichever is the larger, preferably at least three times.

The partitions 8 and 9 are designed in a preferred embodiment so that they are displaceable parallel to the upper and lower covers 6 and 7 in order to adapt the device according to the invention to different characteristic substrate dimensions.

Such design options are known per se to the person skilled in the art. For example, the dividing walls can be displaced in guide rails or fixed in passages or receiving devices in the side and / or top and bottom covers.

In a further preferred embodiment, the partitions 8 and 9 are designed such that the distance d1 or d2 to the lower or upper covers 7 or 6 can be varied in order to adapt the device according to the invention to different characteristic substrate dimensions.

Such design options are known per se to the person skilled in the art. For example, several partitions can be arranged telescopically together, so that they can be extended or shortened by pulling them out.

The distances d1, d2, d3 and b are preferably chosen so that the distances between the substrate and the walls are as equal as possible in order to ensure the most uniform possible flow around the substrate in the inert atmosphere. The cross-sectional area formed thereby can be round, oval, ellipsoidal, quadrangular, trapezoidal, rectangular, square or irregular in shape. For the sake of simplicity, the cross-sectional area is preferably quadrangular and particularly preferably rectangular or square. For the sake of simplicity, the inlet 13 and outlet 14 can only consist of openings in the front 2 or rear 3, or possibly also in a lateral 4 or 5 cover. Of course, input 13 and output 14 may also be mounted in the upper 6 or lower cover 7.

In a preferred embodiment, input 13 and / or output 14 are made longer, so that the substrate is conveyed a distance 15 with the length f1 through the input 13 and / or a distance 16 with the length f2 through the output 14 , These distances f1 and / or f2 may, for example, be 0 to 10 times the parameters d1 or d2, depending on which of these two parameters is the larger, preferably 0 to 5 times, particularly preferably 0 to 2-fold, most preferably 0.5 to 2-fold and especially 1 to 2-fold (Figure 1).

In a further preferred embodiment, the input 13 and / or output 14 are designed so that the substrate is enclosed as closely as possible. This can be achieved, for example, so that the openings of input and / or output come as close as possible to the dimensions of the substrate and not, as required above, form a multiple of the substrate cross-section. If the input and / or output are extended, the cross-sectional area of the extended embodiment can taper in the direction of the input or output.

In a further preferred embodiment, input 13 and / or output 14 are provided with devices which reduce leakage of the inert gas contained in the device from the input or output. Since the substrate at the entrance is usually coated with an uncured, ie sticky, coating composition, such devices should not touch the substrate at the entrance.

Examples of suitable devices are screens, brushes, curtains, curtain strips, fine meshes, springs, doors, sliding doors or locks. Of these, if desired, several can also be connected in series. Pre-and post-flooders at the inputs and / or outputs are also suitable. Pre- and post-floods are tanks containing inert gas for the purpose of separating air-vortex zones from the irradiation zone. For this purpose, the inert gas tank can be extended from the exposure zone both in the height and on both sides in the width. The dimensions of the receiving waters are primarily dependent on the rate of entry and exit and on the geometry of the substrate.

If both inputs and outputs are provided with such devices, then it is a preferred embodiment to open and close inputs and outputs simultaneously with these devices. This means that in the period in which a substrate passes through the entrance and the device there, for example a door, sliding Door, shutter or lock, is opened, at the same time a hardened substrate passes through the Aus¬ gang and the device located there is also open.

However, if the device according to the invention is set up in a drafty location, then it may be preferable to close the input and output reciprocally, since such a passage through the device according to the invention can be avoided.

In another preferred embodiment, the inlet and / or outlet can also be provided with devices which reduce turbulence or flow. These may be, for example, guide plates 17 or grids arranged along the conveying direction, a plurality of finely meshed nets connected in series or guide plates 18 arranged transversely to the conveying direction, which preferably are adapted as close as possible to the substrate cross section (FIGS. 5 to 8).

In a preferred embodiment of the invention when using an inert gas that is lighter than air, the inlet 13 and / or outlet 14 of the device according to the invention are mounted in the lower half of the device relative to the height h of the device preferably in the lower third and most preferably as far as possible below or in the lower cover 7 (Figure 1).

In a preferred embodiment of the invention when using an inert gas which is heavier than air, the inlet 13 and / or outlet 14 of the device according to the invention are mounted in the upper half of the device, relative to the height h of the device preferably in the upper third and very particularly preferably as far as possible at the top or in the upper cover 6 (FIG. 9).

The conveying mechanism 12 serves to convey the substrate S through the device. Such conveying mechanisms are known per se and not erfindungswesent¬ Lich. The conveying mechanism can be arranged through the device above, below or laterally of the substrate. In a preferred embodiment, the substrate is moved through the device by a one-sided or two-sided laterally arranged conveying mechanism. This has the advantage that no abrasion from the conveying mechanism falls on the possibly still uncured substrate.

The promotion of the substrate can be done for example on conveyor belts, chains, ropes or rails. If desired, the substrate may also rotate within the device according to the invention, but this is less preferred according to the invention.

If objects other than three-dimensional are conveyed through the device according to the invention, for example fibers, films or floor coverings, then the conveyor device 12 can consist of rollers and / or rollers, via which the substrate is conveyed. The device according to the invention contains at least one radiation source 10.

The radiation curing can be carried out with electron beams, X-rays or gamma rays, NIR, IR and / or UV radiation or visible light. It is an advantage of the inventive hardening under inert gas atmosphere that the radiation curing can be done with a wide variety of sources of radiation and low intensity.

Radiation sources which can be used according to the invention are those which are capable of emitting high-energy radiation. High-energy radiation is in this case electromagnetic radiation in the spectral NIR, VIS and / or UV range and / or electron radiation.

With NIR radiation here electromagnetic radiation in the wavelength range of 760 nm to 2.5 microns, preferably from 900 to 1500 nm is designated.

UV radiation or daylight comprises light in the wavelength range of λ = 200 to 760 nm, more preferably of λ = 200 to 500 nm and most preferably λ = 250 to 430 nm.

The radiation dose for UV curing, which is usually sufficient to cure the coating composition, is in the range from 80 to 5000 mJ / cm ² .

By electron radiation is meant irradiation with high-energy electrons (150 to 300 keV).

Preference according to the invention is given to NIR and / or UV radiation and particularly preferably radiation having wavelengths below 500 nm. Very particular preference is given to radiation having a wavelength of less than 500 nm and an exposure dose on the substrate of more than 10 seconds than 100 mJ / cm ^{2 of} the substrate surface.

Can be considered lamps that have a line spectrum, that is radiate only at certain wavelengths Be¬, z. B. LEDs or lasers.

Also suitable are lamps with a broadband spectrum, that is, a distribution of the emitted light over a wavelength range. Intensity maxima are preferably in the range below 430 nm.

Suitable radiation sources for radiation curing are, for example, low-pressure mercury lamps, medium-pressure lamps with high-pressure lamps as well as fluorescent tubes, pulse emitters, metal halide lamps, electronic flash units, whereby Radiation curing without photoinitiator is possible, or Excimerstrahler. Mercury radiators may be doped with gallium or iron.

Radiation curing in the process according to the invention can also be effected with daylight or with lamps which serve as a substitute for daylight. These lamps emit in the visible range above 400 nm and have in comparison to UV lamps only little or no UV light components. Called e.g. Incandescent lamps, halogen lamps, xenon lamps.

Also suitable are pulsed lamps e.g. Photo flash lamps or high-performance flash lamps (VISIT company). A particular advantage of the method is the usability of low energy and low UV lamps, e.g. of 500 watt halogen lamps, as they are used for general lighting purposes. As a result, it is possible to dispense with both a high-voltage unit for the power supply (in the case of mercury-vapor lamps) and, if appropriate, light-protection measures. Also, there is no danger from exposure to ozone in the case of halogen lamps, as is the case with short-wave UV lamps. This facilitates radiation curing with portable irradiation devices and "on-site" applications, ie independent of fixed industrial curing plants, are possible.

As many radiation sources as desired can be used for the curing, each of which may be the same or different.

Optionally, a radiation source arrangement adapted to the substrate geometry and to the conveying speed is also possible in order to expose specific areas in a more intensive manner.

In order to expose regions which are difficult to access, especially from three-dimensional substrates, it is conceivable that at least a part of the radiation sources and / or at least a part of existing reflectors is made movable, for example on robot arms, so that, for example, shadow areas lying within substrates are also exposed can.

It may also be useful during the passage through the device according to the invention to treat the substrate first with NIR radiation and then with UV radiation.

The duration of the irradiation depends on the desired degree of hardening of the coating or of the shaped body. In the simplest case, the degree of hardening can be determined by debonding or scratch resistance, for example, with respect to the fingernail or against other objects such as pencil, metal or plastic tips. Likewise, in the paint sector, usual resistance tests to chemicals, For example, solvents, inks, etc. suitable. Without damage to the paint surfaces, it is above all spectroscopic methods, in particular Raman and infrared spectroscopy, or measurements of the dielectric or acoustic properties, etc. that are suitable.

Since the radiation sources usually provide a large amount of waste heat, which can have damaging effects on temperature-sensitive substrates, it may be expedient not to install the radiation sources completely inside the interior of the device according to the invention, but to mount the radiation sources in such a way that. Kühlvorrich¬ tions of the radiation sources are applied outside the device according to the invention and the radiation sources radiate into the device according to the invention.

This can be achieved, for example, by virtue of the fact that the radiation sources are embedded in the upper or lower cover 7 and / or in the lateral covers 4 and / or 5 and the housings and / or cooling units are outside the device according to the invention.

In a preferred embodiment of the invention, the radiation sources are completely mounted within the device according to the invention, so that the waste heat for an optionally required drying of the coating composition on the substrate can be used (see below).

Furthermore, in order to increase the utilization of the high-energy radiation, one or more reflectors may be provided in the device according to the invention, for example mirrors, aluminum or other metal foils or bare metal surfaces. In a preferred embodiment, the surfaces of the walls or covers 2, 3, 4, 5, 6, 7, 8 and / or 9 may themselves be designed as reflectors.

The at least one radiation source 10 may be positioned in the device according to the invention, based on the total path length of the conveying device by the device according to the invention preferably in the range of 25% of the total path length up to 80% of the total path length, particularly preferably in the range of 33% to 75% of the total path length, more preferably in the range of 40% to 75% and in particular in the range of 50% to 75% of the total path length.

This information refers to the path length of the conveyor by the device according to the invention, i. at the entrance, this path length is 0%, at the exit 100% and in the middle 50% of the total path length.

The at least one radiation source can also be distributed over a wide range, so that a zone is formed within which is irradiated. In a particularly preferred embodiment, at least one radiation source 10 is located in front of the gas supply device 11, viewed in the conveying direction of the conveying device 12, very particularly preferably at least one radiation source 10 is located on the lateral covers 4 and / or 5 and / or on the dividing walls 8 and / or 9 (Figure 10).

This causes the flow of the inert gas, at least between the inlet 13 and the gas supply device 11 preferably in countercurrent to the conveying direction of the conveyor 12 extends.

In principle, the inert gas can be metered into the device according to the invention at any desired point through at least one gas supply device 11.

The flow of the inert gas can in principle move in cocurrent or in countercurrent with respect to the conveying direction of the conveyor 12, preferably the inert gas is metered in so that the flow of the inert gas between the inlet 13 and the Stre¬ bridge, at the radiation curing of the substrate takes place, moved in countercurrent to Förder¬ direction.

Preferably, the inert gas is metered in the region around and / or after the last radiation source, more preferably within a quarter of the total path length of the conveyor by the inventive device before and / or behind the zone within which is irradiated, most preferably in the range from to up to 15% of the total path length before and up to 25% behind the zone in which irradiation takes place and in particular within the range of up to 5% of the total path length before and up to 15% behind the zone within which irradiation takes place.

With the gas supply device 11, a gas or gas mixture can be guided into the inner space or formed there. The latter is of interest, for example, if the inert gas in solid, for example dry ice, or liquid form, for example as condensate or under pressure, is introduced into the apparatus according to the invention and then sublimated or evaporated there.

In a preferred embodiment of the invention, the inert gas is flow and vortex low in the device according to the invention passed, for example by Strömungsvergleichmäßiger or flow straightener, such as perforated plates, sieves, sintered metal, grids, frits, beds, honeycomb or tubular structures, preferably perforated plates or grids. By such Strömungsvergleichmäßiger or flow rectifier an oblique flow or a swirl are reduced. The addition amount of the inert gas is adjusted in accordance with the invention so that the losses of inert gas are compensated by any leaks or through the inlet and / or outlet. It is of course desirable to keep the consumption of inert gas as low as possible. In general, with the device according to the invention, the addition of inert gas to compensate for the loss of inert gas in addition to the inert gas volume displaced and exhausted via the conveyed material is not more than twice the internal volume of the device according to the invention per hour, more preferably not more than the simple Internal volume, most preferably not more than 0.5 times and in particular not more than 0.25 times the internal volume of the device according to the invention per hour.

In a preferred embodiment of the present invention using an inert gas which is lighter than air, the inert gas is fed via a gas supply device 11 in the upper third of the device according to the invention, with respect to their height h, more preferably in the upper quarter and most preferably in the upper cover 6.

In a further preferred embodiment of the present invention when using an inert gas which is lighter than air, the inert gas is heated before, during or after the metered addition via a gas supply device 11, for example to a temperature which corresponds at least to the temperature of the protective gas atmosphere, particularly preferably to a temperature, the temperature at least 10 ⁰ C above the Tempe¬ the protective gas atmosphere is located and very particularly preferably to a Tempera¬ structure which is at least 20 ⁰ C above the temperature of the protective gas atmosphere.

In a preferred embodiment of the present invention when using an inert gas which is heavier than air, the inert gas is supplied via a Gaszuführungsvor¬ direction 11 in the lower third of the device according to the invention, with respect to des¬ sen height h, particularly preferably in the lower quarter and most preferably in the lower cover 7.

In a further preferred embodiment of the present invention when using an inert gas which is heavier than air, the inert gas is cooled before, during or after the metered addition via a gas supply device 11, for example to a temperature which is below the temperature of the protective gas atmosphere be¬ Sonders preferably to a temperature at least 10 ° C below the temperature lies Tempera¬ the inert gas atmosphere, and most preferably to a Tempera¬ structure, is at least 20 ⁰ C below the temperature of the protective gas atmosphere.

It represents a further preferred embodiment of the invention, in the device according to the invention, to use nitrogen and carbon dioxide simultaneously as inert gases, with nitrogen via a gas supply device 11 in the upper third the device according to the invention, based on the height h, fed, particularly preferably in the upper quarter and very particularly preferably in the upper cover 6 and carbon dioxide via a gas supply device 11 in the lower third of the inventive device, based on the height h, supplied, especially Preferably in the lower quarter and most preferably in the lower cover 7 is supplied. In a further embodiment of this embodiment, the nitrogen can be heated as described above and / or the carbon dioxide can be metered cooled as described above. As a result, a density gradient of the inert gases can be achieved within the device according to the invention by overlaying.

The lateral covers 2, 3, 4 and / or 5, as well as the upper and lower Abde¬ ments 6 and / or 7 are designed in a preferred embodiment thermostatically controlled or isolated to a temperature compensation between the device according to the invention and the environment as low as possible to keep. By compensating the temperature via the outer walls, unwanted convection currents could occur within the device.

Of course, the device according to the invention can have one or more manholes or accesses through which the interior space is accessible, in order for example to move partition walls, to change the distances d1 and / or d2 or to replace lamps. Before entering the device, the inert gas should be removed from the interior and the radiation sources switched off, for safety reasons.

Application, film formation, evaporation of diluents and / or thermal Vor¬ reactions of the coating composition is usually carried out outside of the erfindungs¬ proper device.

In this case, according to the invention, it generally does not matter in which temporal or spatial distance from the device according to the invention or in which way the application takes place.

The application can be applied to the substrate, for example, by spraying, filling, doctoring, brushing, rolling, rolling, casting, laminating, dipping, flooding, brushing, etc. The coating thickness is usually in a range of about 3 to 1000 g / m ² and preferably 5 to 200 g / m ² .

In a particularly preferred embodiment of the invention, the substrate coated with a coating compound is dried at least partially within the device according to the invention, ie, volatile components of the coating composition are largely removed within the device. Such volatile constituents may be used, for example, in the coating. act mass contained solvents act. These may be, for example, esters, for example butyl acetate or ethyl acetate, aromatic or (cyclo) aliphatic hydrocarbons, such as, for example, xylene, toluene or heptane, ketones, for example acetone, isobutyl methyl ketone, methyl ethyl ketone or cyclohexanone, alcohols, for example ethanol, isopropanol, Mono- or lower oligoethylene or propylene glycols, mono- or di-etherified ethylene or propylene glycol ethers, glycol ether acetates, such as, for example, methoxypropyl acetate, cyclic ethers, such as tetrahydrofuran, carboxylic acid amides, such as dimethylformamide or N-methylpyrrolidone, and / or water. The evaporation and / or evaporation of solvents in the drying step within the device according to the invention has the advantage that the gaseous solvents within the dust-free device contribute to the inert atmosphere, which reduces the consumption of inert gas, and additionally has a softening effect on the treatment during curing. stratification, which makes it more flexible. Therefore, it is advantageous according to the invention if the inert gas atmosphere present in the device according to the invention is at least 2.5% by volume, preferably at least 5, particularly preferably at least 7.5% and very particularly preferably at least 10% by volume having one or more solvents.

In a further particularly preferred embodiment, the device according to the invention additionally has a condensation possibility 19 (FIG. 11) in which the solvents present in the inert gas atmosphere within the device according to the invention can be condensed out. Such condensation possibilities are preferably located at the input and / or output of the device according to the invention. These may be, for example, plate or shell-and-tube heat exchangers, cooling coils or cold fingers which are operated either with an external cooling medium in cocurrent or countercurrent, preferably in countercurrent to the conveying direction of the substrate, or preferably in the case of dry ice as a source of CO ₂ as an inert gas within the Vorrich¬ device to be operated with dry ice, whereby at the same time inert gas is generated within the device and the solvent can be recovered. The condensate is then collected and conveyed outside the device, for example by means of a lift, outflow or discharge, optionally with a siphon. By means of such condensation and, if appropriate, reuse of the solvent, the emissions and the consumption of solvent are markedly reduced.

For drying the coating composition on the coated substrates within the device according to the invention, the inert gas atmosphere and / or the coating composition over a period of at least 1 minute, preferably at least 2 minutes, more preferably at least 3 minutes and most preferably at least 5 min a temperature of at least 50 ⁰ C, preferably at least 60 ⁰ C, more preferably at least 70 ⁰ C and most preferably at least 80 ⁰ C heated.

The heat for the drying can be introduced, for example, by utilizing the waste heat of the at least one radiation source 10 or via at least one additional heating device 20, which is located between the inlet and the irradiation of the coated substrates. Such heaters 13 are known per se to those skilled in the art, it is preferably IR and / or NIR emitters that heat the coating composition. With NIR radiation here electromagnetic radiation in the wavelength range of 760 nm to 2.5 microns, preferably from 900 to 1500 nm, with IR radiation, the wavelength range of 25-1000 microns (far IR) and preferably 2.5-25 microns (middle IR). For drying, radiation with a wavelength of 1 to 5 μm is preferably used.

In a preferred embodiment, the radiation is at least partially, preferably fully performed if the coating composition to the be¬ coated substrates at a temperature of 50 ⁰ C or more, preferably of at least 60 ⁰ C, more preferably of at least 70 ⁰ C, and most preferably of at least 80 ^° C. It is of minor importance how the coating composition is brought to this temperature, whether by heating the inert gas atmosphere and / or by radiation sources 10 and / or by additional heating devices 20 and / or in another way.

If the radiation curing is carried out at least in part at such an elevated temperature of the coating composition, better properties are found in the coating thus obtained. The reason for this is unclear, for example, could be a reduced viscosity of the heated coating composition.

The residence time within the device depends on whether additional drying is to take place within the device according to the invention or not. Usually the residence time without drying within the device according to the invention, ie from the passage of the substrate through the entrance to the passage of the exit, is at least one minute, preferably at least 2 minutes, more preferably at least 3 minutes, most preferably at least 4 minutes and in particular at least 5 min. The residence time without drying within the device according to the invention as a rule does not exceed 15 minutes, preferably it is not more than 12 minutes, more preferably not more than 10 minutes, very particularly preferably not more than 9 minutes and in particular not more than 7 min. Although a higher residence time generally has no adverse effect on the curing of the coating composition, it also has no positive effect and thus leads to unnecessarily large devices. Contains the device according to the invention still an additional drying, so of course the time for drying must be added to the specified residence time.

The length of the Fördererinrichtung 12 by the device according to the invention and the speed of conveying the substrate is adapted accordingly to this residence time. The residence time of the substrate in the device depends, for example, on the substrate, as well as its size, weight and complexity of its structure, as well as reactivity, type (for example pigmentation), amount, thickness and area of the coating composition to be hardened or of the coating containing it from the substrate.

The conveying speed of three-dimensional objects through the device according to the invention can be, for example, 0.5 to 10 m / min, preferably 1 to 10 m / min, particularly preferably 2 to 8 m / min, very particularly preferably 3 to 7 and in particular 5 m / min. Objects with gas-producing parts, such as trim parts or housings for vehicles or machines, are conveyed at a similar speed, but require additional measures to reduce the oxygen input, in particular by means of extended travel distances.

Three-dimensional objects are those whose coating with a coating composition could not be at least theoretically cured by direct irradiation from exactly one radiation source.

For web goods, such as films or floor coverings, the conveying speed can be up to over 100 m / min and for the fibers to over 1000 m / min. In these cases, the conveyor 12 may include, for example, rollers and / or rollers.

It can be useful to provide two or more parallel conveying devices within the device, which convey the substrates through a common input and output but pass through separate paths within the device. This has the advantage that the number of inputs and outputs over which most of the inert gas is lost is kept as low as possible.

In order to avoid the losses of inert gas, the device according to the invention should be set up in a draft-free location, since inert gas can already be sucked out of the device according to the invention by a slight flow which flows around the device. Of course, however, for reasons of safety, adequate ventilation of the location of the device must be ensured in order to avoid an inerting of the surroundings, which could jeopardize the operating personnel. In order to minimize the inert gas requirement in the device according to the invention, air flows which are present via air exchange at application and drying devices can be reduced by keeping corresponding distance to these application and drying devices or by redirecting or breaking these air flows with, for example, shielding walls.

Radiation-curable coating compositions contain radiation-curable compounds as binders. These are compounds with free-radically or cationically polymerizable ethylenically unsaturated groups. The radiation-curable composition preferably contains from 0.001 to 12, more preferably from 0.1 to 8 and very particularly preferably from 0.5 to 7, mol, of radiation-curable ethylenically unsaturated groups per 1000 g of radiation-curable compounds.

As radiation-curable compounds come z. For example, (meth) acrylic compounds, vinyl ethers, vinylamides, unsaturated polyesters e.g. based on maleic acid or fumaric acid optionally with styrene as reactive diluent or maleimide / vinyl ether systems into consideration.

Preference is given to (meth) acrylate compounds, such as polyester (meth) acrylates, polyether (meth) acrylates, urethane (meth) acrylates, epoxy (meth) acrylates, carbonates (meth) acrylates, silicone (meth) acrylates, acrylated polyacrylates.

Preferably, at least 40 mol%, more preferably at least 60%, of the radiation-curable ethylenically unsaturated groups are (meth) acrylic groups.

The radiation-curable compounds may contain other reactive groups, e.g. Methylamine, isocyanate, epoxide, anhydride, alcohol, carboxylic acid groups for additional thermal curing, eg. B. by chemical reaction of alcohol, carboxylic acid, amine, epoxy, anhydride, isocyanate or melamine groups, contain (dual eure).

The radiation-curable compounds may be e.g. as a solution, e.g. in an organic solvent or water, as an aqueous dispersion, as a powder.

The radiation-curable compounds and thus also the radiation-curable compositions are preferably free-flowing at room temperature. The radiation-curable compositions preferably contain less than 20% by weight, in particular less than 10% by weight, of organic solvents and / or water. They are preferably solvent-free and water-free (so-called 100% systems). In this case, it is preferably possible to dispense with a drying step. In addition to the radiation-curable compounds, the radiation-curable compositions may contain other components as binders. Suitable examples are pigments, leveling agents, dyes, stabilizers, etc.

For curing with UV light, photoinitiators are generally used.

Photoinitiators known to those skilled in the art may be used as photoinitiators, for example. those in "Advances in Polymer Science", Volume 14, Springer Berlin 1974 or in K.K. Dietliker, Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints, Volume 3; Photoinitiators for Free Radical and Cationic Polymerization, P.K.T. Oldring (Eds), SITA Technology Ltd, London.

Suitable examples are phosphine oxides, benzophenones, α-hydroxy-alkyl aryl ketones, thioxanthones, anthraquinones, acetophenones, benzoins and benzoin ethers, ketals, imidazoles or phenylglyoxylic acids.

Phosphine oxides are, for example, mono- or bisacylphosphine oxides, such as, for example, Irgacure® 819 (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide), as described, for example, in EP-A 7 508, EP-A 57 474, DE-A 196 18 720, EP-A 495 751 are described or EP-A 615 980, for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin ^® TPO), ethyl 2,4,6-trimethylbenzoylphenyl phosphinate, bis (2,6-dimethoxybenzoyI) -2 , 4,4-trimethylpentylphosphine oxide,

Benzophenones are, for example, benzophenone, 4-aminobenzophenone, 4,4'-bis (dimethylamino) benzophenone, 4-phenylbenzophenone, 4-chlorobenzophenone, Michler's ketone, o-methoxybenzophenone, 2,4,6-trimethylbenzophenone, 4-methylbenzophenone, 2 , 4-dimethylbenzophenone, 4-isopropylbenzophenone, 2-chlorobenzophenone, 2,2'-dichlorobenzophenone, 4-methoxybenzophenone, 4-propoxybenzophenone or 4-butoxybenzophenone

α-hydroxy-alkyl-aryl ketones are, for example, 1-benzoylcyclohexan-1-ol (1-hydroxycyclohexyl-phenylketone), 2-hydroxy-2,2-dimethylacetophenone (2-hydroxy-2-methyl-1-phenyl- propan-1-one), 1-hydroxyacetophenone, 1 - [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, polymer containing 2-hydroxy-2- contains methyl-1- (4-isopropen-2-yl-phenyl) -propan-1-one in copolymerized form (Esacure® KIP 150)

Examples of xanthones and thioxanthones are 10-thioxanthenone, thioxanthen-9-one, xanthen-9-one, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dichlorothioxanthone, chloroxanthenone . Anthraquinones are, for example, β-methylanthraquinone, te / f-butylanthraquinone, anthraquinonecarbonyl acid ester, benz [de] anthracen-7-one, benz [a] anthracene-7,12-dione, 2-methylanthraquinone, 2-ethylanthraquinone, 2-terf-butylanthraquinone , 1-chloroanthraquinone, 2-amylanthraquinone

Acetophenones are, for example, acetophenone, acetonaphthoquinone, valerophenone, hexanophenone, α-phenylbutyrophenone, p-morpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, p-diacetylbenzene, 4'-methoxyacetophenone, α-tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1-indanone, 1, 3,4-triacetylbenzene, 1-acetonaphthone, 2-acetonaphthone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1, 1-dichloroacetophenone, 1-hydroxyacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-2 -on, 2-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one

Benzoins and benzoin ethers are, for example, 4-morpholinodeoxybenzoin, benzoin, benzoin isobutyl ether, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether, 7-H-benzoin methyl ether,

Examples of ketals are acetophenone dimethyl ketal, 2,2-diethoxyacetophenone, benzil ketals, such as benzil dimethyl ketal,

Phenylglyoxylic acids as described in DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761 or other photoinitiators, such as benzaldehyde, methyl ethyl ketone, 1-naphthaldehyde, triphenylphosphine, tri-o-tolylphosphine, 2,3-butanedione or their mixtures, such as 2-hydroxy-2-methyl-1-phenyl-propan-2-one and 1-hydroxycyclohexyl-phenylketone, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 2- Hydroxy-2-methyl-1-phenylpropan-1-one benzophenone and 1-hydroxycyclohexyl phenyl ketone, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,4,6-trimethylbenzophenone and 4-methylbenzophenone, 2,4,6-trimethylbenzophenone and 4-methylbenzophenone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide,

It is an advantage of the invention that the content of the photoinitiators in the radiation-curable composition can be low.

Preferably, the radiation-curable compositions contain less than 10 parts by weight, in particular less than 4 parts by weight, more preferably less than 1.5 parts by weight of photoinitiator per 100 parts by weight of radiation-curable compounds.

Sufficient is in particular an amount of 0 parts by weight to 1, 5 parts by weight, in particular 0.01 to 1 part by weight of photoinitiator.

The radiation-curable composition can be applied by conventional methods to the substrate to be coated or brought into the appropriate form.

The radiation curing can then take place as soon as the substrate is surrounded by the protective gas.

The inventive method is suitable for the production of coatings on substrates and for the production of moldings.

Suitable substrates are, for example, wood, paper, textile, leather, fleece, Kunststoff¬ surfaces, glass, ceramics, mineral building materials such as cement bricks and Faserzementplatten, or metals or coated metals, preferably plastics or metals, for example, as films may be present.

Plastics are for example thermoplastic polymers, in particular poly methyl methacrylates, rephthalate Polybutylmethacrylate, polyethylene terephthalates, polybutylene, Polyvinylidenflouride, polyvinyl chlorides, polyesters, polyolefins, Acrylnitri- lethylenpropylendienstyrolcopolymere (A-EPDM) ₁ polyetherimides, polyether ketones, polyphenylene sulfides, polyphenylene ethers or mixtures thereof.

Also mentioned are polyethylene, polypropylene, polystyrene, polybutadiene, polyesters, polyamides, polyethers, polycarbonate, polyvinyl acetal, polyacrylonitrile, polyacetal, polyvinyl alcohol, polyvinyl acetate, phenolic resins, urea resins, melamine resins, alkyd resins, epoxy resins or polyurethanes, their block or graft copolymers and blends of it.

Preferred plastics include ABS, AES, AMMA, ASA, EP, EPS ₁ EVA, E-VAL, HDPE, LDPE, MABS, MBS, MF, PA, PA6, PA66, PAN, PB, PBT, PBTP, PC, PE , PEC, PEEK, PEI, PEK, PEP, PES ₁ PET, PETP, PF, PI, PIB, PMMA, POM, PP, PPS, PS, PSU, PUR, PVAC, PVAL, PVC, PVDC ₁ PVP, SAN, SB, SMS, UF, UP plastics (abbreviated to DIN 7728) and aliphatic polyketones.

Particularly preferred plastics as substrates are polyolefins, e.g. PP (polypropylene), which may optionally be isotactic, syndiotactic or atactic and optionally non-oriented or oriented by uni- or bisaxial stretching, SAN (styrene-acrylonitrile copolymers), PC (polycarbonates), PMMA (polymethyl methacrylates), PBT (Poly (butylene terephthalate) e), PA (polyamides), ASA (acrylonitrile-styrene-acrylic ester copolymers) and ABS (acrylonitrile-butadiene-styrene copolymers), as well as their physical blends (blends). Particularly preferred are PP, SAN, ABS, ASA and blends of ABS or ASA with PA or PBT or PC.

As molding may be mentioned z. B. composites z. B. containing radungshärtba¬ rer mass impregnated fiber materials or fabric, or molded body for stereolithography.

Claims

claims

An apparatus 1 for carrying out a curing of coatings on a substrate S under an inert gas atmosphere, comprising - side covers 2, 3, 4 and 5, upper and lower covers 6 and 7, wherein 2, 3, 4, 5, 6 and 7 Commonly enclose an interior, one or more partitions 8, which divide the interior, the partition walls 8 complete with the lower cover 7 and leave a distance d1 to the upper cover 6, one or more partitions 9, which divide the interior , wherein the partitions 9 terminate with the upper cover 6 and leave a distance d2 to the lower cover 7, wherein 8 and 9 with the respective adjacent partition wall 9 or 8 and, if appropriate, the side covers 2 or 3 a divided Innen¬ space (Compartment) form, at least one within the interior and / or in the interior of radiating radiation source 10, at least one gas supply device 11, with a gas ode Gas mixture can be guided or formed in the interior, at least one conveyor device 12 for the substrate S, inlet 13 and outlet 14,

in which

the partitions 8 are substantially perpendicular to the lower cover 7, the partitions 9 are substantially perpendicular to the upper cover 6, the distances d1 and d2 and the width b of the device 1 are chosen so that they are greater than the dimensions of Substrate S along the conveying direction of the conveying device 12 and by the devices 2, 3, 8 and 9 at least 4 compartments are formed.

2. Device according to claim 1, characterized in that the cross-sectional area through which the substrate is conveyed through the individual compartments in the Vorrich¬ device, amount to at least three times the projected cross-sectional area of the substrate in the conveying direction.

3. Device according to claim 1 or 2, characterized in that the number of compartments is 4 to 15.

4. Apparatus according to claim 1 or 2, characterized in that the number of compartments is 6 to 8.

5. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the inert atmosphere consists predominantly of nitrogen and / or Kohlenstoffdi¬ oxide.

6. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the inert atmosphere has an oxygen content below 3% by volume.

7. Device according to one of the preceding claims, characterized marked, that the height h of a compartment is at least twice as large as the larger of the distances d1 or d2.

8. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the partitions 8 and 9 do not deviate more than 30 ° from the vertical with the covers 7 and 6 respectively.

9. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the cross-sectional areas, as defined in claim 2, not more than six times as large as the projected cross-sectional area of the substrate S in the conveying direction.

10. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the radiation source 10 comprises a UV wavelength λ of 200 nm to 760 nm.

11. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the radiation source 10 comprises a NIR and / or IR wavelength λ of 760 nm to 25 microns.

12. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the gas supply via the gas supply device 11 aerodynamically er¬ follows.

13. Device according to one of the preceding claims, characterized marked, that the input 13 is formed over at least one length f1, which is 0 to 10 times the parameter d1 or d2, depending on which of these two Parameter is the larger, is.

14. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the output 14 is formed over at least a length f2, which is 0 to 10 times the parameter d1 or d2, depending on which of these two parameters is the larger , is.

15. Device according to one of the preceding claims, characterized gekennzeich¬ net that input 13 and / or output 14 are sealed by suitable means against Gasab- flow.

16. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the inert gas is heavier than air and the inert gas via a gas supply device 11 in the lower third of the device 1, based on the height h, supplying.

17. The apparatus according to claim 16, characterized in that the inert gas is added via a gas supply device 11 at a temperature which is below the temperature of the inert gas atmosphere.

18. The apparatus according to claim 16 or 17, characterized in that the input 13 and / or output 14 of the device in the upper half of the device, relative to the height h of the device, are mounted.

19. Device according to one of claims 1 to 15, characterized in that the inert gas is lighter than air and the inert gas via a Gaszuführungs¬ device 11 in the upper third of the device 1, based on the height h, supplying.

20. The apparatus according to claim 19, characterized in that the inert gas is added via a gas supply device 11 at a temperature which is above the temperature of the inert gas atmosphere.

21. The apparatus according to claim 19 or 20, characterized in that the input 13 and / or output 14 of the device in the lower half of the device, relative to the height h of the device, are mounted.

22. Device according to one of the preceding claims, characterized gekennzeich¬ net, that the side covers 2, 3, 4 and / or 5, as well as the upper and lower covers 6 and / or 7 are designed thermostatically or isolated.

23. Method for carrying out a curing of coatings on a substrate S under an inert gas atmosphere, characterized in that the curing is carried out in a device according to one of the preceding claims.

24. The method according to claim 23, characterized in that the temperature in the device is at least partially 50 ⁰ C or more.

25. A method for carrying out a curing of coating compositions on a substrate S under an inert gas atmosphere, characterized in that one carries out the curing at least partially at a temperature of the coating composition on the coated substrate S of at least 5O ⁰ C.

26. Use of a device according to one of claims 1 to 22 for carrying out a curing of coating compositions on a substrate S.