WO2010084144A1

WO2010084144A1 - Method for examining the output of uv emitters in a printing machine by means of uv-reactive media

Info

Publication number: WO2010084144A1
Application number: PCT/EP2010/050669
Authority: WO
Inventors: Rainer Gebhardt; Matthias Rapp
Original assignee: Manroland Ag; Paul, Eva
Priority date: 2009-01-26
Filing date: 2010-01-21
Publication date: 2010-07-29
Also published as: DE102010001079A1; DE102010001079B4

Abstract

The invention relates to a method for controlling a printing machine, which is used in particular to print UV-reactive printing inks, wherein the emitter output of a drying device should be monitored in order to ensure the processing of printing inks and paints that are cured by radiation. The radiation output is monitored by means of UV-reactive pigments that are introduced into the coating and that react to UV irradiation with a color change. The degree of polymerization of the printing inks and/or paints is determined inline, meaning during the printing process, or offline, meaning outside of the printing machine after the printing process. Characteristic values for the emitter output are derived from the respective detection of the color change of the pigments. By using doped printing sheets at regular intervals in stacks of sheets, the quality of the drying in a print order can be continually documented.

Description

manroland AG

Method for checking the performance of UV lamps in a printing press by means of UV-reactive media

The invention relates to a method for checking the power of UV lamps in the control of a printing press, in particular when using radiation-curing inks.

Radiation-curing offset printing inks have become widely used in today's printing industry and are widely known. The advantages of printing with radiation-curable printing inks are the fast, spontaneous crosslinking after irradiation with a UV radiation source, the solvent-free nature of the printing inks and the good printability of non-absorbent substrates.

Conventional printing inks are either oil-based or solvent-based. Oil-based inks dry on the one hand by the oxidation of the oil-based binders and the simultaneous so-called knock-off, i. by penetration of color components in the absorbent substrate of the printing substrate. On the other hand, the drying also takes place by evaporation of the volatile oils in the printing ink (heat-set method). In contrast, radiation-curing printing inks and coatings cure by a photochemical process, which is also referred to as crosslinking. The liquid or uncrosslinked printing ink film is converted into a solid state by the polymerization under the action of UV light.

But there have been known cases of error in which uncrosslinked ink constituents were transferred by imitation in the delivery stack of a sheet-fed press or by Abklatsch in a roll after printing on the back of the overlying substrate. Also, inks components can migrate through the substrate. A migration of printing ink constituents or a print-off of printing inks can lead to a sensory influence on the contents during packaging. If specific migration limits are exceeded, it can not be ruled out that the consumer will be harmed in the case of food packaging. If the specific migration limits are exceeded, packaging must definitely be withdrawn from circulation, which, in addition to the financial consequences, usually also results in a loss of the reputation of the brand manufacturer in the market. The preservation of health safety is paramount. According to §30 LMBG, it is forbidden to produce consumer goods in such a way that, when used as intended, they are likely to damage health by their material composition, in particular by toxicologically active substances or impurities. In addition, according to German and European law, as well as in the USA, the "no-migration principle" applies, ie a transition from substances to the packaged foodstuff is to be avoided, which is why it is especially important to crosslink the radiation-curing printing ink on the substrate to make sure.

Another problem arises from the operation of the printing press. If radiation-curing printing ink or varnish layers on the printing substrate are not sufficiently through-hardened and the machine operator pulls test specimens, for example for checking the print quality, migration-capable constituents of the radiation-curing printing inks can be absorbed via the skin. In addition to the health hazards, irritation and alergic reactions of the skin may also develop.

Another problem in printing operation arises from the fact that sheets with uncrosslinked printing ink or paint components are usually treated as hazardous waste. This requires a logistical overhead and usually generates additional costs for disposal. Printing presses already have devices and methods that avoid the amount of waste. For example, the UV dryers on the machines of well-known manufacturers are already connected to the press control. Only when the UV dryer selected by the operator returns its readiness for operation to the printing press control can the printing be started. This measure avoids that printed sheets are produced with non-crosslinked printing inks or varnishes. If for any reason a spotlight fails, so the feeder of the machine, and thus the sheet feed, locked and the pressure is interrupted.

However, these solutions only consider the case where the radiator has a total failure. However, emitter power and intensity must be individually adjusted and adjusted for each print job in order to achieve the best possible result. In most cases, it is not possible to produce the obvious solution with maximum emitter power in order to ensure reliable crosslinking of the printing ink or coating film, since in addition to the useful radiation, thermal radiation is also transferred to the printing substrate. In the case of heat-sensitive substrates, for example thin films, this can lead to a change in the dimensions of the substrates and distortions, which as a consequence usually also have register problems with the printing. The quality of UV printing depends on the operating time of the lamps, the pollution of the reflectors and the change in the spectral characteristics of the radiation distribution. The radiation power must also be adapted to the substrate used, the printing inks and varnishes used and the printing speed. Among other things, the performance of film hardening is also significantly influenced by the pigmentation of printing inks. A dark ink, such as black, requires more energy than a light ink, as the dark pigment absorbs a high proportion of the UV radiation and consequently this part of the radiation is no longer available for the curing process. The performance data of a UV lamp, which are usually given in watts / cm, give no statement about the actual effective UV power and the spectral properties of the radiator. With a modern UV control system, the printer should be able to set up the process immediately after the curing process.

It has been proposed on various occasions to monitor the emitted radiation power and radiation distribution of the UV lamps inline. Systems for inline process control, for example, offer the option, for example, of reading the lamp power required for the optimum curing result at the start of production. With modern surveillance systems, monitoring of intensity and power can be monitored using a spectrometer. Shifts in the spectrum or lamp power can then be restored at any time by a closed loop.

Such a control method is described in US 4,032,817. As possibilities for adaptation to the current operating conditions of the processing plant, the adjustment of the lamp power, but also the adjustment of the processing speed of the production plant is mentioned.

The disadvantage of such quality measuring systems lies in the fact that the curing result is indirectly deduced from the lamp output. Thus, changes in the production conditions, for example, temporary fluctuations in the applied layer thickness and the production speed could possibly influence the curing result, without the lamp power changing in its spectral characteristic or in its power. Currently, however, many buyers of printed matter are required to obtain a statistic or even a 100% quality statement on order-based printed products. The background of such a desire is quite understandable, as the manufacturer of the products is most affected by the loss of image, and thus undoubtedly connected loss of sales. An indirect follow-up However, knowledge about the spectral measurement of the lamp power is only an indication of the through-polymerization of the printing ink or varnish layers, but offers no guarantee for this.

It would be much better on the printed product inline or offline to determine the curing of the ink or varnish layers. For example, the dynamic curing of enamel coatings and pigmented ink layers can be determined by Real Time FTIR (Fourier Transform Infrared) techniques. Application examples for this can be found u. a. in the paper, Bo Jang, "Study of Pigmented UV Curable Systems by Real Time FTIR," Sartomer Company, Exton, PA (www.sartomer.com/wpapers/5035.pdf).

For this purpose, a suitable infrared measurement technique is also known. In a first application, the sample is irradiated by a pulse source with infrared spectra in a fixed, variable pulse length and pulse rate, and the remitted radiation is detected by a sensor and evaluated by evaluating the integration time and readout time. This enables a highly dynamic measurement of the photon pulses.

Furthermore, a method for controlling a printing press is known from DE 10 2006 015 277 A1. In the printing press, which is used in particular for printing UV-reactive printing inks, measures are used to control the machine power, the emitter power and optionally a marking device of a printing press for processing radiation-curing inks and varnishes. The degree of polymerization of the printing inks and / or paints is determined inline, ie during the printing process, or offline, ie outside the printing press after the printing process. Characteristics for the control of the radiator output, the engine power and / or for the actuation of marking devices are derived from the respective measurement. This allows reliable values for drying gain by means of radiation curing layers with increased effort. Also, an evaluation is usually only selectively possible.

The object of the invention is therefore to create a method on a printing machine, by means of which a good evaluability of the drying effect can be achieved both locally on the printed sheet and in relation to the radiator output.

The solution of the problem is designed according to the features of claim 1.

The invention describes a method for controlling a printing machine, preferably an offset printing machine, wherein the degree of polymerization of the printed dye or lacquer layers is detected directly on the substrate by a color change. On the basis of these values of the color change, it is then possible to influence the controls and controls of the printing machine and of the units connected to the printing press. This achieves high quality and secure production with radiation-curing printing inks.

The measurement on the printing substrate with the printed ink or varnish layers can take place "inline" in the printing machine, whereby suitable sensors are arranged above the printing cylinder or in the area of the delivery of a sheet-fed printing press or at any position above the web of a web-fed printing press Often it will be sufficient to carry out measurements only on critical components of the print, for example consisting of high layer thicknesses or dark ink layers, since sufficient curing of such critical areas of the printed matter can be achieved It is safe to assume that even the simpler areas have sufficient polymerization.

The inline measuring system can be installed via one or more printing cylinders of a printing press. It makes sense to have at least one measuring device to install over the printing cylinder of a printing unit, preferably after the last printing unit, and a measuring system after the coating unit. Paints are often applied flat and a measurement of the ink layers would then no longer be easily possible if only one measuring system after the coating unit would be installed.

In another embodiment of the invention, the measurement is carried out "offline", wherein the test sample, for example a printed sheet or parts of a printed sheet, for example, is placed in an analyzer or in the simplest way directly taken into consideration "Inline" measurement disadvantageous because it still requires an activity of a machine operator. Consequently, it is up to the machine operator how close the control of the polymerization process is. A 100% control, as with the inline measurement is not possible.

According to the invention, however, both measuring methods, "inline" or "offline", which can be used in combination or alternatively, are connected directly to the machine control and / or the drive for the UV lamps or UV lasers.

In the case of insufficient curing of the ink or varnish layers, the lamp power can then be adjusted immediately in a closed control loop, for example by increasing the energy supply to the UV emitter and / or switching on other UV emitters.

However, it is not always possible to increase the irradiance, for example, because there are no more line reserves, or because the substrate no longer tolerates additional heat input, which is associated with an increase in performance, at least when using conventional HG medium pressure lamps. In this case, the printing press production output is reduced until the polymerization characteristics or measured values determined by the measuring equipment are displayed. be recovered, again reflect adequate polymerization. In a particular embodiment, the maximum speed of the printing press is limited to the printing speed, which ensures just a sufficient polymerization of ink and varnish layers. In this way, it can be avoided that the operator intentionally or unwillingly does not consistently produce polymerized signatures.

In a simple embodiment of the invention, one or more measures, or one or more characteristic values are displayed to the machine operator on the printing machine control station, which indicates the degree of polymerization.

In the simplest case, this could be a "traffic light" with three panels: RED: - insufficient polymerization, YELLOW: - critical polymerisation limit, borderline and GREEN: - complete polymerisation.) In this case, the operator must react automatically and either reduce machine power or increase the irradiation energy on the printed sheet.

In a further embodiment of the invention, all printed sheets that appear to be insufficiently cured by the measuring device, marked by one or more mark on the sheet edge or in the sheet surface, or by a utility-related marking. In the case of a usage-related marking, the marking serves to be able to discharge the marked benefits later in the further processing. The reverse case, the marking of all vouchers is of course conceivable. Markers can be made in a known manner by ink jet printers, by laser printers, by laser, by spray heads or by pens with an invisible or visible mark.

In the UV printing process UV / LED spotlights are used to cure paint and varnish layers. Due to the irradiation of UV light, the curing takes place by polymerization of a UV or paint system applied from an applied UV ink or varnish system. standing coating instead. The printing process can be done eg in offset, flexo, screen or digital printing units. For the complete curing of the coating the entry of a minimum amount of energy is necessary so that a complete polymerization and thus a sufficient sufficient curing of the paint and varnish layer can be generated.

UV lamps experience a decline in performance over their use. The life of UV lamps is e.g. depending on the frequency of restarts, the operation with correct cooling, the pollution of the spotlights, this mainly affects their edge areas, and the maximum for the Trocknungsbzw. Hardening process used radiator power.

By reducing the lamp power, it is necessary to control it at certain time intervals to ensure sufficient UV power for sufficient curing. Especially in the area of packaging, which are in direct contact with the content, there is a potential health risk. Increasingly, those involved in the process chain must prove that quality specifications for production have been adhered to.

Previously used measuring systems for detecting UV radiation can be divided into the following groups, for example:

1. Laboratory measurement on a test bench; The measuring principle used is: UV sensor / temperature sensor

2. monitoring the UV power in machine; The measuring principle used is: UV sensor measuring cell, quartz tube and UV sensor as a mobile or fixed measuring rod or measuring cell.

3. Inline measurement in the printing press at substrate height as measuring principle is used: photometric transmitted light measurement of UV-sensitive film strips / color change of the measuring strip depending on the UV output Problems or deficits arise when the variants listed below are used to check the UV radiation intensity. These are as follows:

To 1. Laboratory measurement (test bench)

- no inline measurement is possible in the machine

After performing a system calibration, previously acquired values are no longer usable as comparison values

- Method with the lowest measuring rate

to 2. Inline monitoring of UV power

- Each UV spectrum requires its own measuring cell

- The dose of UV radiation can not be determined

- Measuring systems that are used in the printing press can easily be polluted by powder or paper dust

- A high accuracy is constantly questioned by possible operating errors of the staff

On 3. Inline measurement in the printing press at substrate height - the test strips are sensitive to light and temperature

- There are large deviations

- Measurement inaccuracies can be caused by the operator

- The measurement process is designed by the application of test strips on the sheet as quite complex - it is only punctual measurement possible, but not the measured value over the entire format length and format width

- No measurements are possible for UV-A radiation

The present invention is based essentially on the nature of the method of a UV emitter power control in the printing machine. For two applications comes a UV-reactive medium, in the form of a modified ink or a mo- difiziert pressure varnish, used. This UV-reactive medium undergoes a color change when exposed to UV light

A first method according to the invention serves to carry out an online control with a detectability of the drying result.

The UV-reactive test medium is applied during the production process while running, inside the printing press, before passing through a workstation with UV irradiation. This process can take place either partially (see FIG. 5: test area outside the print image area) or flatly (see FIGS. 1 to 4: test area over the entire image area). Furthermore, the process is continuously carried out as a follow-up control or it is discontinuously used to generate a slip sheet for the work result. The process of applying the UV-reactive test medium to the printing material can take place here in a direct or indirect way. The UV reactive test medium could e.g. by means of an array of inkjet printheads in a printing station on a sheet selected as a test sheet over its entire printing area or at selected locations are applied.

By irradiating UV light at a respective drying station, a color change of the UV-reactive test medium, e.g. here in the form of a modified inkjet ink, in the coating on a sheet coated as a test sheet. This gives a follow-up control to ensure a constant check to ensure UV irradiation to cure the coating with sufficient performance to complete cure.

Alternatively, the UV-reactive test medium can also be applied flat in a flexographic printing unit of the printing press, that is, for example, in a coating unit with anilox roller. By using an imaged high-pressure plate, the test medium can also be applied specifically in certain areas. A second procedure is used to check the lamp power of the UV lamps used for drying.

The lamp power of a UV drying system is reduced over the period of use and method of use. In order to ensure a sufficient radiation power of the UV lamps for sufficient curing, the radiated power delivered must be controlled at certain time intervals. The UV-reactive test medium can be applied to test sheets in the form of a modified varnish as a separate test medium or as an admixture to an existing varnish using a conventional varnishing unit. The application can be made over the entire surface over the entire sheet format. The test sheets are exposed to a correspondingly applied paint coating in a sheet delivery of the printing machine, as under normal production conditions, the radiation of the UV lamps installed in the press. As a result of the irradiation of the UV light, a color change of the UV-reactive test medium then takes place in the paint coating. This color reaction is identifiable and allows a review of the lamp performance over the entire format length and format width.

The evaluation of the condition of the UV drying unit can be carried out by comparing the color change either visually, densitometrically or colorimetrically. For this, an evaluation mechanism (color location / density vs. UV dose / color comparison scale or similar) must be used. This can be done either manually outside the machine or as an inline measurement, which can give feedback on the machine performance, if necessary to readjust the radiator output. As a further embodiment, an automatic control sequence for distinguishing the state of individual UV lamps is possible, ie UV lamp lamps or LEDs are activated separately and their power distribution is documented. The resulting maintenance protocol, whereby the evaluation can be done manually or automatically as described above, then provides a statement as to where performance deficiencies of the dryer system must be specifically eliminated. A third procedure is the continuous monitoring of print jobs where UV drying is used.

As an alternative to the controlled and in-line introduction of UV-reactive, liquid test medium, UV-reactive pigments can already be applied in a planar or partial manner on a printing sheet / format sheet. These printed sheets can then be processed as a test or slip sheet during ongoing production. Already provided in the stack of printing material on a sheet-fed press such test sheets are inserted at defined intervals and then allow a continuous detection of the radiator power during the edition. By evaluating the color change, this can serve to safeguard the process with regard to the UV lamp output.

The test sheets can be marked and recognized by means of an evaluation device. The marking may also be applied during inline coating as described above. Even then, the test sheets can easily be sorted out automatically.

It is known in this context that in sheet-fed presses by means of so-called bow switches, it is possible to deliberately discard and store such test sheets.

In principle, therefore, a drying process in the printing operation can be monitored in each case with the above-described first and third methods and the drying result can be documented. Furthermore, with the second procedure, the printing press can be controlled with regard to its setting and general functionality with regard to the drying with UV lamps and optionally readjusted.

The invention will be explained below with reference to exemplary embodiments with drawings. Show in it

Figures 1 to 4 possible evaluation examples on the basis of the inventive method, Figure 5 shows an embodiment of the method according to the invention for partial test areas and Figure 6 is a flowchart for performing the method.

FIG. 1 shows a printing substrate as a printed sheet B with a printed image. The printing process now takes place as a test run for the printing press or as a production process for a series of printed sheets to be coated.

The sheets B are moved in a transport direction R by a sheet-fed press. They are coated there and then dried. On the printed sheet, which are provided as a test sheet, a layer of UV-reactive pigments is incorporated either in the coating to be applied or in a pre-coating. These UV-reactive pigments can change color with correspondingly intense UV radiation. The color change (color change) leads to a change in the optical effect of the coating of the test sheet.

This result of the color change is shown by way of example in FIGS.

FIG. 2 shows a discoloration of the coating of the printed sheet B that drops from right to left (see black arrow below) and thus transversely to the direction of sheet travel R. This shows that on the right edge of the print sheet, the UV irradiation has led to a sufficient cure, while on the left side of the coating has been too little or not cured.

The reason for this may be that the UV lamps are worn out, unevenly soiled, the light output within a UV lamp is irregular or at Interconnection of several UV lamps bring individual UV lamps too little radiant power.

The detected non-uniformity of the radiation power can be eliminated by controlling the corresponding UV lamps and in the limit case by cleaning or lamp replacement.

FIG. 3 shows a discoloration of the coating of the printed sheet B falling from top to bottom (see black arrow on the right) and thus in the sheet running direction R. This means that in the region of the upper edge of the print sheet B, the UV irradiation has led to a sufficient hardening, while in the region of the lower edge, the coating has been too little or not cured.

The reason for this may be that the luminous efficacy inside the UV lamps is uneven for a long time or that the printed sheet flutters in the area of the dryer, so that the distance to the UV radiator is uneven. Likewise, the UV emitter can be set too far away from the sheet path, so that it does not radiate sufficiently intensively onto the printed sheet B at the beginning of the sheet (lower edge of the printing sheet B).

The detected non-uniformity of the radiation power can be eliminated by static or dynamic readjustment of the corresponding UV lamps and by improving the sheet guidance in the drying area.

FIG. 4 shows a discoloration of the coating of the printed sheet B that drops from top to bottom (see black arrow on the right) and from left to right (see the black arrow below) and thus in the sheet running direction R and from left to right. This means that in the area of the upper, left-hand corner of the print sheet B the UV radiation has led to sufficient hardening, while in the area of the lower, right-hand corner the coating has been cured too little or not at all. The possible causes for this have already been described above and overlap in this case.

A printed sheet B, which is uniformly colored by the method according to the invention after UV irradiation, may, however, be incompletely dried, by the way. Depending on the admixture of the UV-reactive test medium, it must therefore be determined exactly for which pigment density of the UV-reactive pigments which UV irradiation power results and which discoloration occurs in this case.

Ideally, the discoloration of all used or inline-produced test sheets is completely uniform and sufficiently strong in color change. Thus, the function of the drying device of the printing press can be detected as satisfactory. If, nevertheless, the coating does not harden sufficiently, another factor which may be considered is insufficient doping of the coating medium with UV-reactive curing constituents. Then, the per se intended polymerization and thus the curing of the coating can not get started.

In summary, it can thus be said that the invention is based essentially on the type of method of a UV radiator power control in the printing press. For two application examples, a UV-reactive medium, in the form of a modified ink, a modified printing ink or a modified printing ink, is used. This UV-reactive medium undergoes a color change when exposed to UV light. It must be processable and printable for the printing process used, comparable to a conventional ink, printing ink or conventional varnish. The modified printing ink must be measurable densitometrically during processing, ie before irradiation, in order to be able to dose and apply a reproducible ink layer thickness. The UV-reactive medium must continue to remain thermally stable and lightfast both before, during and after irradiation.

The UV-reactive medium can be used for an online to a printing process feasible control of the drying effect.

During the production process, the UV-reactive medium is co-applied, inside the printing press, before passing through the drying station of a UV lamp. On the one hand, this process can be partial or planar in its distribution on the printed sheet, and on the other hand, it is carried out for a continuous follow-up control or discontinuously for producing selectively outputable document sheet.

In the continuous control, the application of the UV-reactive medium can be carried out on each sheet, in which, for example, corresponding drying measurement fields are integrated into an existing print control strip. The UV-reactive medium for forming the drying measuring fields can then be applied via a separate printing unit. In this case, the machine configuration can be considered by the order of the UV-reactive medium is carried out according to a respective dryer arrangement or dryer connection. It should be noted that at least the UV lamps to be monitored come to effect only after the application of the UV-reactive medium.

The application of the UV-reactive medium to the substrate can be direct or indirect, i. z. B. on an inkjet printing device at decidedly selected points on the sheet or as a test medium on a flexographic printing, such as a paint module of an offset printing press, or in the normal printing process on a conventional printing unit of a printing press.

The irradiation of the UV light causes a color change of the UV-reactive medium which has been applied, for example, in the form of a modified inkjet ink or a modified varnish (printing varnish) or a modified printing ink. There- By continuously obtaining measurement objects and readings for on-going inspection to ensure complete verification of the printed products and to ensure sufficient UV power provided for sufficient curing.

Furthermore, the proposed method can be used for checking the lamp power of dryers in printing presses. The lamp power of a UV dryer or spotlight system deteriorates during the period of use and also depending on their mode of use. In order to be able to ensure sufficient UV output of the dryer system for reliable or at least sufficient curing of printed products, the radiator output must be controlled at certain time intervals. The control of the spotlights can be done at commissioning of the printing press and at different time intervals. This can be done on a specific substrate to ensure comparability.

The UV-reactive medium can be applied in the form of a modified lacquer or a modified printing ink as a separate test medium or admixture to an existing lacquer or a paint over a conventional coating unit or printing unit. The application can be made across the entire sheet format. The sheet with the applied paint or the applied paint is exposed in the delivery and after each printing unit, as under normal production conditions, to the UV lamps installed in the system. The irradiation of the UV light causes a color change of the UV-reactive medium. This allows a review of the lamp power over the entire format length and format width. This can be done as the sum of all UV / UV LED emitters installed in the machine, or separately for each individual emitter located in the machine.

The evaluation of the condition of the UV emitter can be done by comparing the color change either visually, densitometrically or colorimetrically. This is based on an evaluation algorithm for balancing the drying effect with a measured value, in which, for example

a color location and / or a color density at the spot spot and an associated UV dose and

- a color comparison scale

be related to each other.

The densitomethsche or colohmetric (colorimetric) measurement can be done either manually outside the machine, ie offline, or as an inline measurement, which can give a feedback to the machine performance, if necessary to readjust the radiator output.

As a further embodiment, an automatic control sequence for discriminating the state of individual UV emitters is possible, i. Lamps / LEDs are activated separately and their power distribution is documented. The resulting maintenance report (evaluation manually or automatically, see above) then provides a statement as to where any performance deficits need to be eliminated in a targeted manner.

As an alternative to the UV-reactive, liquid medium, UV-reactive pigments can already be applied to a format sheet (flat or partial). These sheets can also be processed as a test or slip sheet during ongoing production. Already provided in the stack of printing material on a sheet-fed press such test sheets are inserted at defined intervals and then allow a continuous detection of the radiator power during the edition. By evaluating the color change, this can serve to safeguard the process with regard to the UV lamp output.

FIG. 5 shows the variant of an arrangement of test areas for the inline process. In this case, strip-shaped test areas T are provided at the start of the sheet and at the edges. These test areas can be found everywhere in so called pressure-free zones are arranged. There, the UV-reactive medium is applied by means of a printing plate.

The action of the UV emitters will then lead to a color reaction in the test areas T, which can be measured inline or in-line by means of the quality control devices. Thus, the drying effect can be detected both over the width of the printed sheet B and over its length in the transport direction R.

By means of the test surfaces integrated in the print sheet, a continuous monitoring of the drying effect of the UV lamps within the scope of the recorded machine parameters is readily possible.

Finally, FIG. 6 shows a protocol process in the manner of a flowchart. From the executed sequence representation, the following variants of the method according to the invention can be taken by way of example by way of various process sequences for the drying control process and of associated evaluation possibilities:

A) Create individual test sheets / minutes or a reference sheet for the edition inline

1. Evaluation with pre-coated test sheet (UV-reactive pigments are embedded in the sheet or thin layer applied) are selectively inserted in the stack of the investor or fed sequentially by means of a Hilfsaniegers. 2. Coating in the production process

3. Drying / curing with detection of the operating parameters at the printing machine and the UV lamps

4. Measuring the color change on the test / production sheet

5. Evaluation of the color change with regard to through hardening 6. Feedback + / - on machine and dryer control B) Generate test sheet / log sheet continuously inline

1. Evaluation with test or production sheet having test areas T at the edges.

2. Coating in the production process 3. Drying / hardening with detection of the operating parameters at the printing machine and the UV lamps

4. Inline or offline measurement of the color change on the test / production sheet

5. Evaluate the color change with respect to through hardening

6. Feedback + / - on machine and dryer control

C) Generate reference sheet / test sheet offline using a special sheet

1. Evaluation with pre-coated test sheet (UV-reactive pigments are incorporated in the sheet or thin layer applied), sheet feed can be done by a separate feeder or from an auxiliary pile of the investor. 2. Coating in the test process

4. Measuring the color change on the test sheet

5. Evaluation of the color change with regard to through hardening 6. Feedback + / - on machine and dryer control

D) Generate reference sheet / test sheet offline using a normal sheet

1. Evaluation with fully coated test sheet of normal uncoated substrate. 2. Coating in the test process with UV-reactive medium

4. Measure the color change to the test sheet

Claims

claims

1. A control method for the function and / or drying action of a device for drying coatings applied in a printing press from a printing ink and / or a lacquer which is curable by means of radiation, wherein the printing press has at least one UV or Electron beam radiation source for curing the radiation-curable layers, characterized in that - that a radiation-curing ink and / or a through

Radiation-curing paint is added to a radiation, at least UV-reactive reactive admixture, wherein the admixture causes a color change in the admixture upon irradiation,

- That an existing of this ink and / or this coating coating in the printing press at least temporarily on printing substrates for

Production of test sheet is applied, or that at least temporarily with the admixture doped raw sheet fed as a test sheet of the press and coated with paint or ink,

- that the test sheets are subjected to irradiation with coating, - that an evaluation of the color change in the coating takes place during the printing process inline in the printing press or offline outside the printing press on a whole or a part of a test sheet,

in such a way that a distribution of the color change of the coating over the surface of the printing substrate is detected and evaluated with respect to its flat uniformity, and

- That from the data obtained a rating for the quality of the radiator effect in terms of the radiator performance is obtained, with a stronger color change in the coating or in partial areas of the coating mean a stronger UV radiation.

2. Control method for the function and / or drying action of a device for drying applied in a printing press coatings from a printing ink and / or a paint which is curable by means of radiation, the printing machine at least one UV or electrons Radiation radiation source for curing the radiation curable

Having layers, characterized by

in that a radiation-curing printing ink and / or a radiation-curing paint is added to an admixture which is reactive to radiation, at least to UV radiation, the admixture causing a color change in the admixture upon irradiation,

that a coating consisting of this printing ink and / or this lacquer is applied in the printing press at least temporarily to printing substrates for the production of test sheets,

or that at least at times with the admixture doped raw printing sheets are fed as a test sheet of the printing press and coated with lacquer or printing ink,

- that the test sheets with coating undergo irradiation,

- That a determination of a degree of polymerization and / or a degree of cure of the coating takes place on the printing substrate, - that takes place during the printing process inline in the printing press or offline outside the printing press on a whole or part of a test sheet, an evaluation of the color change in the coating .

in such a way that a distribution of the color change of the coating over the surface of the test sheet is detected and evaluated with regard to its flat uniformity, and

- That the data obtained from a rating for the quality of the radiator effect in terms of radiator performance and / or in relation to the curing and / or polymerization of the coating is obtained, with a stronger color change in the coating or in some areas of the coating ein ne mean stronger UV radiation.

3. Control method according to claim 1 or 2, characterized in that a determination of the degree of polymerization of the coating on the

Printing substrate or the acquisition of data resulting from the intensity of the irradiation color change in the coating with a suitable measuring device, wherein the measurement during the printing process inline in the printing machine or offline outside of the printing press on a whole or part of a test sheet.

4. Control method according to claim 1 or 2, characterized in that a determination of the degree of polymerization of the coating on the

Printing substrate or the acquisition of data on a color change resulting from the intensity of the irradiation in the coating by means of on-the-spot, wherein the evaluation takes place outside of the printing press on a whole or a part of a test sheet.

5. Control method according to claim 1 to 4, characterized in that the evaluation of the color change in the coating on the test sheet in an orientation in the sheet travel direction with respect to the driving behavior of the radiation source when starting or in continuous operation or as a function of the machine speed or in dependence of Distance of the radiation source from the printed sheet takes place.

6. Control method according to claim 1 to 4, characterized in that the evaluation of the color change data in the coating on the test sheet in an orientation transverse to the sheet travel direction in terms of aging behavior or contamination of the radiation source.

7. Control method according to claim 3 to 6, characterized in that an adjustment of the radiator power and / or the engine power via the control of the radiation device are complementary.

8. Control method according to claim 1 to 7, characterized in that produced as a test sheet or removed from the print run

Sheet or measured by the measuring device values and derived parameters serve as a quality record on the print run.

9. Control method according to claim 1 to 8, characterized in that a reference sheet is removed with at least one color change indicating coating area from the print run, that in the reference sheet the sufficient curing of the coating / coatings by means of an appropriate measurement method and / or derived characteristics is detected, and that the reference sheet is used on the basis of the color change to compare the curing of coatings on printed sheets from the print run, which also have at least one of the same color change coating area.

10. Control method according to claim 1 to 9, characterized in that the signatures with ink or lacquer layers, the sufficient polymerization of the ink or lacquer layers by a suitable marking device, such as one or more spray heads, one or more ink jet heads, by a or several laser printers, or by one or more laser marking systems, or marked by color pencils as a good sheet or labeled.

11. Quality control system for carrying out the method according to claim 1 to 10, characterized in that the method in connection with a sheetfed offset press with at least one offset printing unit, which optionally has one or more coating units, or with a Bogenlackiermaschine or Bogenfle- xodruckmaschine, optionally one or has several coating units or FIe xodruckwerke, is applied.