PRINTING PROCESS

Printing process

The invention concerns a printing process, in particular to printing on plates and/or bags for the packing of food, on which basis of the seven-color printing with the four basic colours cyanogen, Magenta, yellow and black and three further colors, from which two are orange and green.

Such printing processes are from the GB 2,343,141 A (only six colors), which EP 761,434 A (likewise only six colors) and US 2004/0089184 A (a very special printing process for Golfbälle with 2, 4, 6 or 8 colors) well-known. A further seven-color printing is from that further down details descriptive US 5.751.326 A admits, as seventh color blue is used. All these procedures cannot solve the problems indicated in the consequence.

Food for animal and humans such as soup powder, coffee, drop, firm, stückiges animal fodder, will become, often in bags from multilevel foils packed, other food, in particular liquid, viscose rayon or gelled food, in bowls or cups from plastic or aluminum filled etc., which are locked with so-called plates. Printing these bags and/or plates on represents an important application in the following of the descriptive procedure.

Printing processes are generally based on the principle of the so-called subtraktiven color blending, with which by cyanogen, Magenta and yellow the different colors of the spectrum are produced for the over each other printings of the colors. Thus cyanogen with yellow green, cyanogen with Magenta blue and Magenta with yellow red results in. With over each other printings of all three colors one receives black.

To differentiate of this subtraktiven color blending the additives are color blending, which will receive by projection of different colors on a white underground. One proceeds with the colors red, green and blue, by over each other projection from red and green keeps one yellow, from red and blue Magenta and from green and blue cyanogen. If all three colors are project engineering one above the other, one receives white. The subtraktive color blending, which is closely attached to the actually used pigments, exhibits in practice inevitably a set of deviations from the described ideal, so that the three-color printing understanding rising directly from the theory and does not play a noticeable role with professional printing processes. At least black is still additionally used with the professional pressure, in order to be able to affect the brightness, without affecting the colour and arrive over at a deep clean black, which never really succeeds to the over each other printings of the three basic colours by.

With the material pressure is added still another characteristic that the individual colors, to which in the following always also black is counted, if nothing contrary is stated, in the form of points, which are arranged in a mostly square raster, is applied. Usual rasters have thereby an order of magnitude of 54 raster cells per centimeter, according to 542 = 2916 Rasterzellen/cm2. It is possible for each point of a color, soferne it with usual printing processes, is laid on to lay on in different gradations within the borders of 1% the surface to 100% of the surface of a raster cell (corresponds to the elementary particle of the pressure). With the fact this area specification means that with application only one color with 1% the document is covered to 1% of their surface with the selected color and with 100% to 100%. The latter cannot be achieved however without overlaps, so that the color order of the single point is larger here, as it the 100-fachen of the small 1% - point corresponds.

If now likewise, as it is compellingly necessary for the creation of mixed colors, a spot size by noticeable under 50% is laid on and at least one of the two other colors (excluded black) in a comparable size is laid on, then it comes to overlaps between the individual points, which correspond to the initially mentioned subtraktiven color blending. Since however the single color points for the viewer are closed-up designed too small and too close to be able in order still as single color points are noticed it comes into the eye and/or brain of the

Viewer also to additives a color blending. Despite these Größenund of recognizability conditions it comes when printing on surfaces, which extend over several raster cells, with such a creation of several colors with the viewer to the so-called „Moiree " - effect, i.e., the eye means to recognize a kind succession of elevator layer lines on in such a way printed on surface.

It is now for a long time well-known not to attach parallel to the avoidance of this effect the rasters for the individual colors to each other on the individual prints and/or pressure rollers but in given Winkellagen to each other, whereby the arrangement of the colored points to each other from raster cell to raster cell (no matter, from which the raster one proceeds now) changes and so „for the Moiree " - effect, which is based on the cyclic repetition of the arrangements, avoids.

Above the briefly mentioned EP 761,434 A suggests symmetry for a four-color printing using color seven with 60°-iger, cyanogen with 60°, black with 45° arranging Magenta with 75° and yellow when same orientation as Magenta whereby yellow is to be oriented preferentially differently to black. Over the arrangement with the seven-color printing nothing is stated.

For most of the commercially used press products those not in book form but for example as packing of the kind initially specified to be used, is it is present of great importance that individual colors in completely special, of the customer given quality to be printed to be able. It mostly concerns thereby so-called „house colors ", which facilitate or only make the association of the packing with this enterprise for the consumer possible particularly for the enterprise and. One refers in this connection to the multiple attempts of enterprises to let abstract colors protect as mark for its enterprise and to use such abstract colors with the packing and aimed in the advertisement and dominant. For the meaning and the penetration of such colors it is only thereupon-pointed that a noticeable portion of the basic pupils of Europe of the opinion is that the skin of cows would have the color violet, which shows, how important the pressure quality for packing is. For the Verpaclcungsindustrie this that such colors, decoration colors are called, used additionally to the usual four colors particularly for it, the signature, a certain logo or a part of the products, which on the packing are shown means, to train with these decoration colors in completely certain quality. It essentially became generally accepted to use additionally for the four basic colours three decoration colors. These decoration colors are finished mixed and brought and used after customer defaults standardised (and co-ordinated with the respective printing document) into printering, whereby its use results in the desired results reliably.

In the daily practice of pressing this brings however with itself that when reequipping such a seven-color printer from a printing order to the next the pressure rollers at all seven stations do not only have to be exchanged, but that at the three stations with the decoration colors also all color containers, lines, pumps, etc., completely must be changed, since the decoration colors are not compatible among themselves (from customer to customer). Associated additional expenditure in relation to the stations of the four usual colors is completely enormous and increases beyond that in the last years clearly, since more and more enterprises are not ready, packing material in stock to put separates the packing in ever smaller lot sizes to acquire. They are in addition, not to take over or only heavily to bring to it proportionately ever more largely becoming setup costs.

It exists thus a large need at a printing process, with which without the use of the decoration colors to be done can and which able is, the decoration colors in the given quality print reliably.

Without dealing with this problem more in greater detail, it gave, for example attempts already occasionally for the improvement of the four-color printing in the documents initially specified. At the market thereby the procedure which is descriptive in US 5.751.326 A, is successful. With this procedure additionally for the usual color system of the four-color printing cyanogen, Magenta, yellow and black (CMYK, derived from the English designation) is used the three-color system red, green, blue (RGB), from the original chromaticity diagram becomes from there a color hexagon with the accordingly increased possibilities of the pressure. The block letters mentioned essentially concern themselves with the possibility of receiving existing and/or given collecting mains with usual devices to scanning and the information which are necessary plus black for the purposeful use of the six colors. It is proceeded in such a way in principle that the color gamuts, which cannot be achieved by mixtures in the CMYKVerfahren when overprinting two participants colors with the desired depth of shade and Brillianz to create by inclusion according to color of the RGBSystems lying between them whereby naturally also in this case the appropriate color of the RGB system (surface-moderately dominant) is printed together with the necessary color of the CMYK system (with small surface portion).

Since this block letters concern themselves, as previously mentioned, mainly with the suitable collection of the print format and the allocation on the colors the available, about actual printing and the problems arising there nothing is said.

Although this system under the designation OPAL CLAY/TONE at the market is used occasionally, disadvantages adhere to it, which make in most cases also further the use of decoration colors necessary:

The three been added colors RGB must fulfill the same subtraction conditions among themselves as the original complementary colors CMY, so that by their use „the flat places ", which result when mixing CMY, are expenditure-rounded, but change for nothing in principle at the fact that here actually only the basic principle rotates, in the Farbkreis, a second time are used. In addition it comes that brightness gradations, which are obtained by the additive of black are often hard and unpleasant.

It is now the task of the invention to achieve the above-mentioned goals and create a printing process, which is able, of doing without the use of separate pigment mixtures for the decoration colors and it makes possible to achieve with the usual seven-color printing elements this goal. One obtains these goals according to invention because the seventh color is grey. Thus one reaches surprisingly apart from the extension of the original complementary colors within the critical ranges that by grey shade possibilities are created, which are to be obtained by black not possibly.

Particularly satisfying optical results are obtained, if bending the rasters for black, grey and orange are agreeing selected. It has itself shown that these colors, if, which is not frequent, in a cell of the raster actually two or even all three are even printed, by the dominance of the black and/or grey to no Moiree effect to lead.

Equally it proved as favourable that Magenta and green in rasters with agreeing bending are used, while yellow and cyanogen in rasters with own in each case bending are to be present.

One receives particularly good results, if the rasters, related to which arbitrarily with bending 0°, the following angles exhibit accepted raster of yellow: Cyanogen 15,6°, Magenta and/or green 45,5°, and orange and/or grey and/or black 74,8°. It is naturally not necessary that the raster of yellow actually exhibits bending 0° at the machine, it is only the other rasters in relation to the raster the bending mentioned by yellow to exhibit.

The Dichtewerte of the individual colors a role play in addition, the density is defined as the Briggs logarithm of the quotient of the Remission of the blank surface to the printed on surface. The Remission of the blank surface depends essentially on the material and the structure of the surface, the Remission of the printed on surface depends additionally on the coloring material thickness, so that the definition of the Dichtewertes corresponds to a color with given underground of a statement about the color thickness which can be applied. These Dichtewerte are optimally the following

Cyanogen 1.4 Magenta 1.4 yellow 1.2 black 1,6

Orange 1.2 green 1.1 grey 0.6 AIs outstanding for the procedure according to invention suitable pigments turned out the following:

Cyanogen P.B. 15:4 formula number 74160 CAS: 147-14-8 Magenta P.R. 57:1 formula number 15850:1 CAS: 5281-04-9

Yellow P.Y. 126 formula number 21101 CAS: 90268-23-8 black P.B1. 7/P. Sheet 15:4

Orange P.O. 34 formula number 21115 CAS: 15793-73-4

Green P.G. 7 formula number 74260 CAS: 1328-53-6 grey P.B. 7 formula number 77266 CAS: 1333-86-4

These pigment values are defined in the Colourlndexliste of the Society OF Dyers and Colourists as well as in the Chemical Abstract service register (CAS) and represent commercial sizes. The colormetric definition of the individual colors, certainly with a Spektralphotometer SpectroEye with the serial number 14370 of the company Gretag results in the following values:

Orange one: L* = 68.59 cyanogen: L* = 48.72 black: L* = 15,15

^“7* = 44.64 a* = -37.51 a* = -4.56 b* = 84.11 b* = -51.56 b* = 0,26

C* - 95.22 C* = 63.76 C* = 4.57 h = 62.04 h = 233.96 h = 176,73

Yellow: L* = 85.34 grey: L* = 59.21 Magenta: L* = 43.57 green: L* = 57.58 a* = -6.20 a* = -3.48 a* = 73.39 a* = -58.22 b* = 90.86 b* = 0.78 b* = -2.68 b* = 22.47 C* = 91.08 C* = 3.57 C* = 73.44 C* = 62.41 h = 93.90 h = 167.34 h = 357.91 h = 158,90

The letters and/or „* " are common components of the CIELAB - values and the specialist.