Apparatus for curing coatings applied to a member

An apparatus for curing, by drying and/or hardening, layers or coatings, such as printing colors or inks, laminations, etc., that are continuously successively applied to a member. The lowermost, pigment-containing layers are subjected to a thermal treatment via IR radiation, and the uppermost or cover layer, which forms a lamination, is exposed to UV radiation. The air above that region of the coated member that is subjected to the UV radiation is withdrawn and is blown onto that region of the member that is subjected to IR radiation.

BACKGROUND OF THE INVENTION 
The present invention relates to an apparatus for curing, by drying and/or 
hardening, layers or coatings, such as printing colors or inks, 
laminations, etc., that are continuously successively applied to a member. 
The lowermost, pigment-containing layers are subjected to a thermal 
treatment via IR radiation, and the uppermost or cover layer, which forms 
a lamination, is exposed to UV radiation. 
IR-reactive colors or inks are being used more and more frequently in the 
printing industry. These colors, inks, and lacquers dry very rapidly at 
the surface when irradiated with IR radiation, and are thus dry to the 
touch and to dust. In order to be able to further treat a carrier member 
such as paper or cardboard that has been printed with such colors, for 
example by improving the surface quality of the carrier member with an 
acrylate coating or lamination, the IR-reactive colors must be completely 
and thoroughly dried, since otherwise the printing pattern is spoiled due 
to the fact that the wet color portions run below the lamination in the 
material of the carrier member. It should be noted that the thorough 
drying of IR-reactive colors can in extreme cases take several hours. 
It is therefore an object of the present invention to provide a method and 
apparatus with which IR-reactive colors can be intensely dried in such a 
way that the post treatment of the printed-upon carrier member, for 
example a lamination thereof, can be undertaken immediately, i.e. without 
a transition time, after the IR-treatment without impairing the printing 
pattern.

SUMMARY OF THE INVENTION 
The method of tee present invention is characterized primarily in that the 
air above that region of the coated member that is subjected to the UV 
radiation is withdrawn and is blown into the IR drying mechanism in that 
region of the member that is subjected to the IR radiation. 
As a result of the inventive withdrawal of the air from that region of the 
coated member that is subjected to the UV radiation, and subjecting that 
region of the member that is subjected to IR radiation with this withdrawn 
air, the IR-reactive printing color that is to be dried is, in addition to 
the IR radiation, also acted upon by ozone-rich air. As a result of these 
measures, the oxidation processes that take place during the drying of the 
color or ink are accelerated in such a way that the color is thoroughly 
dried in a minimum amount of time, and the printing pattern is not 
negatively altered by the lamination. 
The additional enrichment of the vicinity of that region of the 
printed-upon member that is exposed to the IR radiation with ozone also 
effects an oxidation of the solvent expelled from the color by the IR 
radiation, as a result of which the environment is not polluted. 
The apparatus of the present invention for carrying out the inventive 
method comprises: an IR drying mechanism that is disposed downstream of 
the last printing mechanism, of a printing press, for applying IR-reactive 
colors; a UV-radiation mechanism disposed downstream of a mechanism for 
applying a lacquer-like UV-reactive coating to the IR-treated printing 
colors on the member; and means for introducing exhaust air from the 
UV-radiation mechanism into the IR drying mechanism. 
The apparatus of the present invention makes it possible to carry out the 
inventive method for curing coatings applied to a member without great 
capital outlay with existing printing presses by introducing the exhaust 
air line from the UV-radiation mechanism into the IR drying mechanism. At 
the same time, post treatment mechanisms, with which in particular the 
solvent expelled from the color would be separated out, can be dispensed 
with for the exhaust air from the IR drying mechanism, this exhaust air 
being the entire exhaust air of the printing press; this contributes to a 
reduction of the operating costs of the printing press while increasing 
the printing capacity due to the rapid drying of the color or ink in the 
IR drying mechanism. 
In order to improve or ensure the positive effects upon the drying of the 
IR-reactive colors, which positive effects originate from the ozone or 
active oxygen of the exhaust air from the UV-radiation mechanism, there is 
disposed, pursuant to a preferred embodiment of the inventive apparatus, 
in the IR drying mechanism, downstream of an IR-radiation member when 
viewed in the direction of transport of the printing press, an ozone 
generator, preferably a rod-shaped high pressure glow discharge lamp, 
especially a mercury-vapor lamp, that, accompanied by the formation of an 
annular chamber, is surrounded by a metal or ceramic jacket, the wall of 
which is provided with openings out of which air, preferably a portion of 
the exhaust air from the UV-radiation mechanism, and which was blown into 
the annular chamber, escapes in the direction toward the color layer or 
layers that are to be treated. As a result of this arrangement of this 
specially embodied high pressure glow discharge lamp within the IR drying 
mechanism, the printing color or ink is subjected not only to an 
additional IR radiation, which is emitted by the jacket that is heated by 
the mercury-vapor lamp. Rather, due to the additional inventive measures, 
the ozone content in the IR drying mechanism, which ozone content 
originates from the exhaust air of the UV-radiation mechanism, is also 
increased. This additional ozone passes with the air from the annular 
space between the jacket and the mercury-vapor lamp, via the openings in 
the jacket wall, into the IR drying device and is blown against the 
surface of the printed-upon member. In so doing, the ozone is formed in 
the annular chamber from the atmospheric oxygen due to the UV radiation 
emitted by the mercury-vapor lamp. It would also be possible to provide an 
additional exhaust mechanism in the IR drying device to act upon the 
region between the IR-radiation member and the glow discharge lamp; this 
contributes to an intimate contact of the ozone with the color that is to 
be dried. 
Pursuant to further specific embodiments of the ozone generator, the jacket 
and/or channels thereof can be made of a non-oxidizable material, of a 
material having catalytic properties for generating ozone, preferably from 
atmospheric oxygen, or of a material that converts short wave radiation, 
especially UV radiation, into thermal radiation. 
Further specific features of the present invention will be described in 
detail subsequently. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to the drawings in detail, the object or member 7 that is to 
be printed on or coated enters in the direction of the arrow C, into the 
last printing mechanism 10 for infrared or IR-reactive colors at the 
discharge end of the printing press illustrated in FIG. 1; the member 7 
leaves the printing press in the direction of the arrow D. Along this 
path, the member 7 travels past guide rollers 11 and passes an IR drying 
mechanism 12, a squeezing and blowing mechanism 23, a coating mechanism 13 
for an ultraviolet or UV-reactive acrylate coating, and a UV-radiation 
mechanism 14. 
Disposed in the IR drying mechanism 12 are an IR-radiation member 15 
directed upon the member 7, and an ozone generator 21, the construction of 
which will be described subsequently with the aid of FIGS. 2 and 3. Also 
extending into the IR drying mechanism 12 is the discharge opening 16 of 
an air line 17 in which is disposed a blower 18. The inlet opening 19 of 
the air line 17 is disposed in the UV-radiation mechanism 14. The air is 
withdrawn from the IR drying mechanism 12 in the direction of the arrow E 
into the atmosphere via an exhaust channel 20 
The UV-radiation mechanism 14 is provided with two high pressure glow 
discharge lamps 22 that irradiate the member 7. 
The ozone generator 21 of the IR drying mechanism 12 illustrated in FIG. 2 
comprises a ceramic jacket 1 in which is concentrically disposed a 
rod-shaped mercury-vapor lamp 2. The length of the jacket 1 corresponds to 
the length of the mercury-vapor lamp 2. Disposed on the outside of the 
jacket 1 is an air-collecting channel 3 that communicates via air inlet 
openings 4 in the wall of the jacket 1 with an annular chamber 5 that is 
delimited by the jacket 1 and the mercury-vapor lamp 2. In addition, 
disposed across from the air inlet openings 4 in the wall of the jacket 1 
is a slot-like air outlet opening 6 that extends over the entire length of 
the jacket 1. The air outlet opening 6 is directed against the 
printed-upon member 7, which passes by in the direction of the arrow A. 
In the embodiment of the ozone generator 21 of the IR drying mechanism 12 
illustrated in FIG. 3, the rod-like mercury-vapor lamp 2 is eccentrically 
disposed in the ceramic jacket 1, the length of which essentially 
corresponds to the length of the lamp 2, and the air-collecting channel 3 
is disposed on the side of the jacket 1 relative to the member 7, which 
passes the ozone generator 21 in the direction of the arrow A. The 
air-collecting channel 3 communicates with the annular chamber 5 via air 
inlet openings 4 in the wall of the jacket 1. The annular chamber 5 merges 
into a channel 8 via a slot-like opening 6 that is disposed approximately 
across from the air inlet openings 4. This channel 8 has a zig-zagged 
shape, and is guided in a curved manner along the outside of that region 
of the ceramic jacket 1 that is remote from the color layer or layers that 
are to be treated. The channel 8 has an outlet 9 that is directed against 
these color layer or layers, and that is embodied as an air jet. 
The manner of operation of the inventive apparatus is briefly described as 
follows: 
The high pressure glow discharge lamps 22 in the UV-radiation mechanism 14 
emit not only UV-radiation that initiates the curing reaction of the 
acrylate coating. These lamps 22 also provide an ozone-rich atmosphere, 
since only a portion of the ozone formed from the atmospheric oxygen under 
the effect of the UV radiation reacts with the acrylate coating during 
curing thereof. This excess ozone, instead of being emitted as pollutant 
into the 
a atmosphere, is inventively drawn off by the blower 18 along with the air 
from the UV-radiation mechanism 14, and is then introduced via the air 
line 17 into the IR drying mechanism 12, where it is converted as a 
reaction-ready oxidizing agent during drying of the IR-reactive printing 
color or ink by the radiation emitted from the IR-radiation member 15. In 
addition to the IR-radiation member 15 and the ozone from the UV-radiation 
mechanism 14, the ozone generator 21 also contributes to the drying of the 
IR-reactive color, and especially to the oxidation of the expelled solvent 
in the IR drying mechanism 12. This contribution of the ozone generator 21 
is realized in that the wall of the jacket 1 of the generator 21 that is 
heated by the mercury-vapor lamp 2 transmits IR radiation onto the moving 
member 7. At the same time, a non-illustrated fan blows ambient air into 
the air-collecting channel S, with this air passing via the air inlet 
openings 4 into the annular chamber 5, in which the air is exposed to the 
UV-radiation of the mercury-vapor lamp 2. This UV-radiation converts a 
portion of the atmospheric oxygen into ozone. The now ozone-rich air 
leaves the annular chamber 5 via the air outlet opening 6 and, in the 
direction of the arrows B, strikes the color surfaces of the member 7 that 
are to be dried. As a result, there is formed in the space between the 
IR-radiation member 15 and the ozone generator 21 in the IR drying 
mechanism 12 an atmosphere that is essentially free of solvent, since the 
solvent, which was released during the drying of the IR-reactive colors, 
was converted into harmless products, especially by the ozone. The exhaust 
gases from the IR drying mechanism 12 are subsequently withdrawn in the 
direction of the arrow E into the atmosphere, free of pollutants, via a 
non-illustrated exhaust mechanism and via the exhaust channel 20. 
In the embodiment of the ozone generator illustrated in FIG. 3, the air 
that is exposed to the UV-radiation in the annular chamber 5 strikes the 
color layer or layers that are to be treated only after it has passed 
through the labyrinth-like channel 8. This contributes to increasing the 
ozone-forming effect of the UV-radiation, which is guided into the channel 
8 via the air outlet opening 6 by reflection. The rear region of the 
jacket 1, relative to the coated member 7, is cooled by the inventive 
channel configuration. In this connection, that region of the jacket 1 
that is remote from the member 7 and acts as an IR emitter, experiences 
only a slight cooling effect from the air blown out of the outlet 9 of the 
channel 8 against the member 7, so that the intensity of the radiation of 
this remote region of the jacket 1 is barely adversely affected. 
Before the printed-upon member 7 enters the coating mechanism 13 for the 
acrylate coating, it passes the squeezing and blowing mechanism 23, in 
which ozone that still adheres, in particular to the dry IR-reactive 
printing dye, is removed. 
The present invention is, of course, in no way restricted to the specific 
disclosure of the specification and drawings, but also encompasses any 
modifications within the scope of the appended claims.