EP1547772B1 - Printing process for producing matte and glossy surfaces - Google Patents

Abstract

Substances with a low surface energy are added to the oil-based matt varnish or printing ink used in a printing process which involves printing or coating in succession with oil-based printing ink, matt varnish or ink (on parts of the printed surface) and transparent gloss varnish (over the whole printed surface). A printing process in which print material, in passing through a printing machine (2) with several printing groups (6, 8, 10, 12) followed by a varnishing group (14), is first printed with an oil-based printing ink (I) in at least one of the groups (6, 8, 10), then coated (in group 12) on parts of the printed surface with an oil-based matt varnish or printed with matt ink (II) (containing a dulling agent), and finally coated over the entire printed surface with a transparent gloss varnish (III) (in group 14). In this process, the matt varnish or matt ink (II) is modified by adding substance(s) (IV) with a low surface energy. An independent claim is also included for products printed on at least one side by this process, using oil-based offset printing ink.

Description

The invention relates to a printing method, in particular a sheet-fed offset printing method in which a substrate after printing by spot coating with transparent paints or overprinting with a matting agent-containing paint on a part of the previously printed area with a matte surface and on another part of the printed area provided with a glossy surface. Due to the different surface texture and the contrast between adjacent matte and glossy faces, for example, different colors of the printed image stand out from each other, give the matt lacquered faces a velvety appearance or the glossy painted faces a reflective, silvery or golden appearance or other appealing visual Achieve effects. The invention further relates to a printed product produced by an offset printing process.

For the production of printed products with juxtaposed matte and glossy faces, it is already known to run the substrate twice in succession through an offset printing press. In this case, the substrate is printed in the first pass in the printing units of the printing press with the desired inks and coated in a downstream coating unit of the printing press either in the area of the later glossy surfaces with a gloss varnish or in the later matte surfaces with a matt varnish, while each remain spared other areas and painted only during the second pass through the printing press. However, this process, in which the second coating application takes place on the already dried printing ink, has three significant disadvantages. First, two passes through the press are required, making the print more expensive. Secondly, it can lead to Passerdifferenzen in the two passes, which can lead to visible overlaps or gaps between the two types of surfaces in the printed image at the boundaries between the matte or glossy faces. Third, both the matt and the glossy paint expensive Photopolymer plates are required, since individual partial surfaces of the printing substrate can not be coated separately with conventional offset printing plates.

DE 200 20 798 U1 already discloses a device for producing spot finishes on substrates in a large-format printing machine, with which the printing material is coated in two of four printing units of the printing machine with a so-called hybrid or UV color system, which is irradiated by irradiation UV light is cured before the substrate is printed in the two subsequent printing units with a typical oil-based offset inking system and finally coated in a subsequent coating tower or coating unit over the entire surface with a colorless paint, which is absorbed to different degrees by the two color systems or to others Way cooperates chemically or physically, thereby affecting the gloss level of the color layers divergent. With this device, it is possible to produce printed products whose surfaces have strongly contrasting matt or high-gloss partial surfaces. For this purpose, however, there is behind a part of the printing units, a UV exposure station required, which requires expensive conversion measures in commercial offset printing machines or is not possible. In addition, hybrid or UV color systems are more expensive than the typical oil-based offset printing color systems and, moreover, have higher toxicity.

Furthermore, EP 0620115 A1 already discloses a device for inline coating of printing substrates in offset printing presses, with which a spot coating of a printing material in one pass is possible. However, the known device requires two of the offset printing units downstream coating units, of which the first, adjacent to the offset printing units coating unit is designed as a flexographic printing and application of rapidly evaporating water-based liquids allowed while the second, downstream coating unit, for example, for full-surface painting of the substrate , With the known device, however, it is not possible to produce printed products which have both very matt and high-gloss painted surfaces which contrast strongly. In addition, offset printing machines are very expensive with the known device and have therefore found no widespread use.

EP 1 237 728 describes a process for decorating cylindrical bodies, with which matt and glossy motifs are produced at the same time by using matting agents, such as matting agents, for the matt motifs. Quartz powder, provided offset color before the subsequent full-surface overcoating with a gloss varnish. Apart from the fact that this is a special printing device for the printing of cylindrical objects, with this method in the end only a limited contrast, i. Achieve difference in gloss value between the matte and the glossy image areas.

Proceeding from this, the object of the invention is to improve a printing method and in particular, but not exclusively, a sheetfed offset printing method such that a printing substrate is produced on commercially available printing machines in a single pass with matte and high-gloss surfaces lying next to one another. Further, the invention is based on the object alone using commercially available offset printing machines and conventional oil-based offset printing inks to produce a printed product with a high contrast juxtaposed matte and glossy surfaces.

This object is achieved with regard to the method specified in claim 1, characterized in that a substrate during a run through an offset or flexographic printing machine (2) with multiple printing units (6, 8, 10, 12) and a downstream coating unit (14 ) is first printed in at least one of the printing units (6, 8, 10) with an oil-based ink, in which the substrate then coated in a subsequent printing unit (12) either on a part of the ink-printed surface with an oil-based matt lacquer or with a matte color is printed, the matting agent or contains, wherein the matte or matte paint one or more substance (s) are added, which have a low surface energy, and in which the substrate thereafter in the coating unit (14) on the entire printed surface is covered with a transparent gloss varnish.

The printing method according to the invention, which in the context of this application comprises both offset printing and flexographic printing processes, can readily be carried out in commercial printing presses, since the partial coating with e.g. the oil-based matte or matte paint in one of e.g. Offset printing can be performed without this needs to be converted or modified. Since the subsequent full-surface coating with the water-based gloss varnish can hardly be carried out in a commercially available coating unit for offset printing presses, to which, however, to improve the gloss value of the later shiny part surfaces expediently some smaller and therefore easy to make changes are made.

The invention is based on the idea not to produce the matt or shiny partial surfaces of the printed product as in the subject matter of DE 200 20 798 by using two different color systems, but by a single color system of oil-based paints or varnishes. In fact, it has been found that the color or lacquer layer modified by its content of particulate matting agents retains a dull appearance because of the low-surface-energy substance it contains, despite a subsequent full-surface application of the gloss lacquer.

This happens u.a. because the gloss varnish applied to the matt varnish or the matt paint is prevented by the admixed substance with low surface energy from wetting the matt varnish or the matt paint well. As a low surface energy fabric of preferably less than 40 milli Newton per meter and especially less than 25 mN / m, e.g. Silicone oil, the known under the name "Teflon" PTFE (polytetrafluoroethylene) or derivatives of these substances, such as hexafluoropropylene, fluorinated ethylene-propylene copolymer (FEP), Hostaflon be used.

According to a further preferred embodiment of the invention, the matte paint or the matt varnish and the gloss varnish are respectively applied before the previously applied glossy printing ink or in the latter case, the previously applied matt varnish is completely cured or struck. This makes it possible, as printing inks or matt lacquer to use conventional oil-based offset inks or an oil-based matt lacquer, which can be applied in each case without additional measures such as UV lamps in offset printing units of conventional offset printing presses on the substrate.

The gloss varnish used is preferably a water-based dispersion varnish, since aqueous dispersion varnishes can be processed well on the varnishing units of commercially available offset printing machines and, on the other hand, provide the desired matt surface in conjunction with the matt or matt varnish, while they do not interfere with the matt varnish coated surfaces provide a high-gloss surface. Preferably, a dispersion paint based on a styrene-acrylate copolymer is used, but also dispersion coatings based on other polymers can be used.

In order to ensure the highest possible contrast between the matt partial surfaces and the shiny partial surfaces, the lowest possible gloss value of the matt partial surfaces and / or the highest possible gloss value of the glossy surfaces is sought.

The lowest possible gloss value of the matt partial surfaces is, according to a preferred embodiment of the invention, supported by the fact that the proportion of matting agents is set as high as is possible without impairing the processing properties and the transparency of the matt lacquer. Finely ground silicates are preferably used as matting agents, although other commercially available matting agents may also be used. Due to the high proportion of particulate matting agent, the matt lacquer has a rough surface, from which the gloss lacquer can be almost completely absorbed, at least in smaller amounts.

A similar effect is achieved when the matte or matte paint only partially wets the previously applied ink, also resulting in a textured surface. Also contributes to the silicone oil or PTFE, which is the matte or matte paint, preferably in a range of 0.2 to 0.6 wt .-%, mixed. The incomplete wetting of the offset printing ink underlay caused, for example, by the silicone oil causes together with the matting agent that the matte lacquer after its application has a uniform, hammer-like, scaly surface.

In order to achieve the highest possible gloss value of the glossy partial surfaces when applying the gloss varnish, but without substantially increasing the gloss value of the matt partial surfaces, further preferred embodiments of the invention provide for a plurality of measures which are carried out alone or preferably in combination.

A first measure is to make the amount of applied gloss paint on the one hand sufficiently large, so that there is a continuous high-gloss surface on the not coated with the matt surfaces, on the other hand, but not so large that it on the previously coated with the matt Partial surfaces cause a complete flooding and leveling of the rough surface. Experiments in this regard have shown that both specifications can be achieved with an application amount between 12 and 14 cm ³ gloss paint per m ² application area, which is why the gloss varnish in the coating unit preferably with the aid of a chamber doctor blade and an anilox roller with a Schöpfvolumen of about 13 cm ³ / m ^{2 is} metered.

A second measure is to use a gloss varnish with a high viscosity, which also counteracts a leveling of the rough surface. Suitably, the viscosity of the gloss varnish more than 70 s ^-1 , preferably more than 75 s ^-1 and most preferably more than 80 s ^-1 , measured according to DIN 53 211. The high viscosity of the gloss varnish is preferably achieved in that the gloss varnish a contains high content of resin, for example in the form of a styrene-acrylate copolymer, said content is suitably more than 20 wt .-%, preferably more than 25 wt .-% and most preferably more than 30 wt .-%.
Since the stated high viscosities of the gloss varnish can lead to difficulties in its processing, provides a further preferred embodiment of the invention to apply the gloss varnish in the heated state on the printed and partially coated with the matt-coated substrate, that is with a temperature of more than 20 ° C, preferably greater than 25 ° C, and most preferably greater than 30 ° C. As a prerequisite for the gloss varnish is expedient in a heated container to a temperature of more heated as 30 ° C and preferably greater than 40 ° C and pumped as needed into the chamber doctor blade. To avoid adhesion of gloss paint on the walls of the container, this is preferably equipped with a stirrer with scrapers.

A third measure is to reduce as much as possible the concentration of a wetting agent normally contained in water-dispersed gloss paints, suitably to less than 3% by weight, preferably to less than 2.5% by weight and most preferably to less than 2 Wt .-%, wherein these values relate to a sulfosuccinate as an example wetting agent. In order to prevent the formation of cracking in the gloss varnish, which is also called crackle or rembrandt effect, as a result of such a low wetting agent content in the subsequent drying of the varnish applied to the wet printing ink and the moist matt varnish, the varnish preferably contains a plasticizer, its content in the gloss lacquer is advantageously between 0.2 to 1.5 wt .-%, and preferably between 0.5 and 1 wt .-%.

In order to enable a fast lubricant-free depositing of the sheet emerging from the coating sheet in sheetfed offset printing or a fast lubrication-free rolling of the printed and coated substrate in web offset printing, provides a further preferred embodiment of the invention, the substrate after coating with the gloss paint at least on the printed Apply hot air and / or heat radiation to the painted side to dry the gloss varnish and the ink more quickly.

With regard to the printed product, the aforementioned object is achieved according to the invention in that a printing material of the printed product, preferably art paper, is printed on at least one side with oil-based offset printing ink is coated on a part of the surface with a matting agent-containing matte paint or matt paint , and coated on the entire printed surface, including the matt coated part surface, with a transparent water-based gloss varnish, wherein the matte varnish or the matte color contains silicone or Teflon or a substance with similar hydrophobic or separating properties.

• Fig. 1: eine schematische Seitenansicht einer zum Spotlackieren dienenden Bogenoffsetdruckmaschine mit mehreren Offsetdruckwerken und einem nachgeordneten Lackwerk.

In the following the invention will be explained in more detail with reference to an embodiment shown in the drawing. It shows:

• 1 shows a schematic side view of a sheetfed offset printing press for spot coating with a plurality of offset printing units and a downstream coating unit.

The commercial four-color sheetfed offset printing machine 2 shown schematically in the drawing consists essentially of a sheet feeder 4 (only partially shown), a total of four offset printing units 6, 8, 10, 12, a printing units 6, 8, 10, 12 downstream coating unit 14, a Drying device 16 and a sheet delivery 18. In the printing press 2, sheets of a printing material, in particular of art paper, spot-varnished after their printing to emphasize different inks by a matte or glossy surface of different parts of the printed image to enhance contrasts, or the To give printing inks a velvety or glossy appearance.

For printing and spot varnishing the sheets in the first, second and third printing unit 6, 8 and 10 are printed one or more colors with commercial oil-based offset inks, then coated in the last printing unit 12 on a portion of the printed area with an oil-based matt lacquer and in the downstream coating unit 14th coated on the entire printed surface with a water-based gloss varnish before they are stored after drying in the drying device 16 as finished printed products by means of the sheet delivery 18 on a sheet stack 20. The printing unit 12 is for this purpose as usual with a printing cylinder 22, a blanket cylinder 24, a plate cylinder 26, an inking unit 28, and a dampening unit 30 equipped with the inking unit 28 is used for metering the matt lacquer, which then transferred together with dampening solution from the dampening unit 30 on the plate cylinder 26 and a pressure plate spanned thereon and the blanket cylinder 24 on the sheet 22 supported by the printing cylinder becomes. In this case, the matt lacquer is applied to those portions of the plate cylinder 26 and the sheet corresponding to the matte faces of the finished printed product, while the dampening solution is applied to the remaining portions, that is, those corresponding to the glossy faces of the finished printed product. The application of the matt lacquer on the offset printing inks is wet in damp, ie before complete drying of the printing inks by knocking off and crosslinking.

The matte lacquer used has a composition similar to the commercial oil-based offset inks, but contains no color pigments, but contains a high proportion of matting agents in the form of finely ground silicates, and 0.2 to 0.6 wt .-% silicone oil or another silicone compound , which ensures that the offset inks applied before the matt varnish are not completely or evenly wetted by the matt varnish. Preferably, a matt lacquer with a very high degree of matting is used, which is offered by Aquaprint GmbH in Hoyen, Germany, under the name Hi Dual 0 700 Matte Litho Lithic.

The printed sheets which have been partially coated with the matt lacquer are then completely coated in the coating unit 14 with the water-based gloss lacquer, which is a modified transparent dispersion lacquer based on a styrene-acrylate copolymer.

In order to prevent the surfaces coated with the matt varnish, which have a surface which is uneven compared with the other part surfaces, being "flooded" with the gloss varnish and thereby being leveled, the proportion of the styrene-acrylate copolymer in the dispersion varnish becomes adjusted more than 25 wt .-%, in order to increase the viscosity of the dispersion varnish (measured according to DIN 53 211) to more than 75 s ^-1 . To avoid difficulties in processing such a highly viscous paint, the coating unit 14 is equipped with a heatable paint container 34 in which the paint at a temperature of about 40 ° C by means of a stirrer with scrapers (not shown) is kept in constant motion, to prevent it from adhering to the walls of the container 34.

In addition, the proportion of sulfosuccinate in the gloss varnish, a wetting agent customary for such transparent dispersion varnishes in offset printing, adjusted to a value of less than 3 wt .-%, most preferably to a content of 2 to 2.5 wt .-%. Since this could possibly lead to cracking (Rembrandt effect) during the subsequent drying of the printed product, 0.1 to 1% by weight of a plasticizer is additionally added to the gloss finish.

In addition, the gloss varnish in the coating unit 14 is applied in a precisely defined limited amount, on the one hand on the not coated with matt varnish surfaces still a sufficient high-gloss surface can be achieved, on the other hand, however, the gloss varnish is almost completely absorbed on the matt lacquered surfaces, without significantly increase the matte value of these surfaces. Experiments have shown that this is the case with a gloss paint amount of about 13 cm ³ / m ² coated substrate surface. For metering the gloss varnish, the varnishing unit 14 is provided with a chambered doctor blade 36 and an anilox roller 38, whose scoop volume is approximately at the above-mentioned value of 13 cm ³ / m ² . From the anilox roller 38, the gloss lacquer is transferred to the sheets by means of a blanket or blanket cylinder 40.

After coating with the gloss varnish, the finished printed product is dried in the drying device 16 with the aid of infrared radiators and / or by supplying hot air at least on the printed and varnished side, before it is deposited on the stack 20.

Under the above-mentioned printing conditions can be obtained using a substrate made of art paper in a printing and Lackierdurchgang by the printing press 2 a printed product, which at the same time, ie side by side, printed faces with a matte or glossy surface, of which the former a gloss value of about 20% and the latter has a gloss value of about 80% (each measured at a light incidence and light angle of 60 degrees), so that the difference is about 60%, which could not be achieved on commercial presses so far.

Claims (29)

1. Printing method wherein a printing material is printed in a single run through an offset or flexographic printing press (2) including a plurality of printing units (6, 8, 10, 12) and a downstream varnishing unit (14) firstly with an oil-based printing ink in at least one of the printing units (6, 8, 10), wherein the printing material is subsequently either coated in a downstream printing unit (12) with an oil-based matte varnish on part of the surface that has been printed with printing ink or is printed with a matte ink, the matte varnish or the matte ink containing matting means with one or more materials having a low surface energy being admixed to the matte varnish or the matte ink, and wherein the printing material is then coated in the varnishing unit (14) with a transparent glossy varnish on the entire printed surface.
2. Method according to claim 1,
   characterized in
   that that the matte varnish or matte ink is applied before the printing ink has hardened.
3. Method according to claim 1 or 2,
   characterized in
   that the glossy varnish is applied before the printing ink and the matte varnish or the matte ink have hardened.
4. Method according to one of the preceding claims,
   characterized in
   that the matte varnish or matte ink contains a high proportion of matting means.
5. Method according to one of the preceding claims,
   characterized in
   that the printing material is coated with a water-based glossy varnish.
6. Method according to one of the preceding claims,
   characterized in
   that the glossy varnish is a dispersion varnish.
7. Method according to one of the preceding claims,
   characterized in
   that the glossy varnish has a viscosity of more than 70 s^-1, preferably of more than 75 s^-1, ideally of more than 80 s^-1, measured in accordance with DIN 53 211.
8. Method according to one of the preceding claims,
   characterized in
   that the glossy varnish is applied in a heated condition to the printed printing material, surface parts of which have been coated with the matte varnish.
9. Method according to one of the preceding claims,
   characterized in
   that the glossy varnish has a temperature of more than 20°C, preferably of more than 25°C, and ideally of more than 30°C when it is applied to the printed printing material, surface parts of which have been coated with the matte varnish.
10. Method according to one of the preceding claims,
    characterized in
    that the glossy varnish is kept in motion in a container at a temperature of more than 30°C and preferably of more than 40°C before it is applied.
11. Method according to one of the preceding claims,
    characterized in
    that the glossy varnish contains less than 3 percent by weight, preferably less than 2.5 percent by weight, and ideally less than 2 percent by weight of a wetting means.
12. Method according to one of the preceding claims,
    characterized in
    that the glossy varnish contains a softening agent.
13. Method according to one of the preceding claims,
    characterized in
    that the proportion of the softening agent in the glossy varnish ranges between 0.2 and 1.5 percent by weight and preferably between 0.5 and 1 percent by weight.
14. Method according to one of the preceding claims,
    characterized in
    that a resin content of the glossy varnish is more than 20 percent by weight, preferably more than 25 percent by weight, and ideally more than 30 percent by weight.
15. Method according to one of the preceding claims,
    characterized in
    that the glossy varnish contains a styrene acrylate copolymer.
16. Method according to one of the preceding claims,
    characterized in
    that the glossy varnish is metered in the varnishing unit using a screen roller with a take-up volume of about 13 cm³/m² of varnished printing material surface.
17. Method according to one of the preceding claims,
    characterized in
    that warm air and/or thermal radiation is applied at least to the printed and varnished side of the printing material after the latter has been coated with the glossy varnish.
18. Method according to one of the preceding claims,
    characterized in
    that the surface energy of the admixed material is less than 40.10^-3 N/m.
19. Method according to one of the preceding claims,
    characterized in
    that the surface energy of the admixed material is less than 25.10^-3 N/m.
20. Method according to one of the preceding claims,
    characterized in
    that the admixed material is silicone oil or PTFE (polytetrafluorethylene) or their derivative.
21. Method according to one of the preceding claims,
    characterized in
    that the percentage of the materials with a low surface energy admixed to the matte varnish is less than 2 percent by weight.
22. Printed product comprising a printing material, which is at least on one side printed with an oil-based offset printing ink and is additionally coated on a printed surface part with an oil-based matte varnish containing matting means or printed with a matte ink with at least one material having a low surface energy being admixed to the matte varnish or the matte ink, and which is coated with a transparent water-based glossy varnish on the entire printed surface including the surface part that is coated with the matte varnish or printed with the matte ink.
23. Printed product according to claim 22,
    characterized in
    that the value of glossiness of the matte surface part that is coated with the glossy varnish is less than 25 percent and preferably less than 20 percent.
24. Printed product according to claim 22 or 23,
    characterized in
    that the value of glossiness of the printing ink that is only coated with the glossy varnish is more than 60 percent, preferably more than 70 percent and ideally about 80 percent.
25. Printed product according to one of claims 22 to 24,
    characterized in
    that the matte varnish has a high content of matting means.
26. Printed product according to one of claims 22 to 25,
    characterized in
    that the glossy varnish contains a softening agent.
27. Printed product according to one of claims 22 to 26,
    characterized in
    that the matte varnish or the matte ink contains a material with a low surface energy of less than 40.10^-3 N/m.
28. Printed product according to claim 27, wherein the surface energy is less than 25.10^-3 N/m.
29. Printed product according to claim 27 or 28,
    wherein the material with a low surface energy is silicone oil, PTFE (polytetrafluorethylene), or a derivative.

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