EP2421713B1 - Multiple-layer flat structure in the form of a printing blanket or a printing plate for flexographic and letterpress printing - Google Patents

Description

The invention relates to a multilayer sheet according to the preamble of claim 1.

• EP 0 844 100 B1
• EP 1 315 617 B1
• EP 2 070 717 A1
• WO 02/096648 A1
• US 5 798 202
• US 5 804 353

Technik des Flexodruckes, S. 173 ff., 4. Aufl., 1999, Coating Verlag, St. Gallen (CH )

• DE 103 18 039 A1
• DE 1940 852 A1

Such a sheet is known, for example, from the following literature:

• EP 0 844 100 B1
• EP 1 315 617 B1
• EP 2 070 717 A1
• WO 02/096648 A1
• US 5,798,202
• US 5,804,353

Technique of flexographic printing, p. 173 ff., 4th ed., 1999, Coating Verlag, St. Gallen (CH )

• DE 103 18 039 A1
• DE 1940 852 A1

According to the current state of the art, the printing layer of the generic sheet with laser engraving in the context of flexo and high pressure usually consists of a photopolymer. For example, there is the printing layer according to the patent EP 1 315 617 B1 from an elastomeric binder, a polymerizable compound, a photoinitiator or a Photoiniatorsystem and a finely divided filler, such as a fumed oxide (silica, titania, alumina). The full-surface crosslinking of this print layer takes place by irradiation with light, for example with actinic light. Finally, a printing relief is engraved by means of a laser in the crosslinked printing layer. The print layer is then also referred to as a relief layer or printing form after the laser treatment.

• Die Herstellung einer Druckfom ist unter Einbezug von mehreren Arbeitsschritten sehr aufwendig.
• Zumeist ist ein Nachstellen des Anpressdruckes beim Drucken mit verschiedenen Geschwindigkeiten bedingt durch die dynamische Steifigkeit des Materials erforderlich.
• Die photopolymere Druckschicht bzw. Druckform zeichnet sich durch geringe Farbüberträge aus.
• Es können Fehler beim Montieren des belichteten photopolymeren Flächengebildes auftreten.
• Der Ausbildung als Rollenware sind Grenzen gesetzt. Zumeist muss der Endverbraucher verschiedene Formate am Lager haben.

However, the following disadvantages are associated with a printing layer of a photogravure photopolymer:

• The production of a Druckfom is very expensive, including several steps.
• In most cases, an adjustment of the contact pressure when printing at different speeds due to the dynamic stiffness of the material is required.
• The photopolymer printing layer or printing form is characterized by low color transfer.
• There may be errors in mounting the exposed photopolymer sheet.
• The training as a role product are limited. In most cases, the end user must have different formats in stock.

To remedy the aforementioned disadvantages, the sheet according to the invention is characterized in that the polymeric material of the printing layer is a vulcanizate.

Vulcanizate is the name for products or product components produced by vulcanization of a vulcanizable polymer mixture - here the printing layer. In this case, the polymer mixture contains one or more rubber component (s). A vulcanizate is characterized by elastic properties. Depending on the type of rubber used, crosslinking is by means of sulfur (e.g., NR) or peroxides (e.g., EPDM). Of particular importance is the thermal vulcanization at temperatures of 130 to 200 ° C. Cold vulcanization or radiation vulcanization can also be used.

With regard to the vulcanizate, the following two variants are used in particular:

option A

• Ethylen-Propylen-Kautschuk (EPM)
• Ethylen-Propylen-Dien-Kautschuk (EPDM)
• Nitrilkautschuk (NBR)
• (teil)hydrierter Nitrilkautschuk (HNBR)
• Fluor-Kautschuk (FKM)
• Chloropren-Kautschuk (CR)
• Naturkautschuk (NR)
• Styrol-Butadien-Kautschuk (SBR)
• Isopren-Kautschuk (IR)
• Butylkautschuk (IIR)
• Brombutylkautschuk (BIIR)
• Chlorbutylkautschuk (CIIR)
• Butadien-Kautschuk (BR)
• Chloriertes Polyethylen (CM)
• Chlorsulfoniertes Polyethylen (CSM)
• Polyepichlorhydrin (ECO)
• Ethylen-Vinylacetat-Kautschuk (EVA)
• Acrylat-Kautschuk (ACM)
• Ethylen-Acrylat-Kautschuk (AEM)
• Siliconkautschuk (VMQ)
• Fluorierter Methylsiliconkautschuk (MFQ)
• Perfluorinierter Propylen-Kautschuk (FFPM)
• Perfluorcarbon-Kautschuk (FFKM)
• Polyurethan (PU)

The vulcanizate is a vulcanized thermoplastic-free rubber mixture containing at least one rubber component and mixing ingredients. As rubber components may be mentioned in particular:

• Ethylene-propylene rubber (EPM)
• Ethylene-propylene-diene rubber (EPDM)
• Nitrile rubber (NBR)
• (partially) hydrogenated nitrile rubber (HNBR)
• Fluoro rubber (FKM)
• Chloroprene rubber (CR)
• Natural rubber (NR)
• Styrene butadiene rubber (SBR)
• Isoprene rubber (IR)
• Butyl rubber (IIR)
• Bromobutyl rubber (BIIR)
• Chlorobutyl rubber (CIIR)
• Butadiene rubber (BR)
• Chlorinated polyethylene (CM)
• Chlorosulfonated polyethylene (CSM)
• Polyepichlorohydrin (ECO)
• Ethylene-vinyl acetate rubber (EVA)
• Acrylate rubber (ACM)
• Ethylene acrylate rubber (AEM)
• Silicone rubber (VMQ)
• Fluorinated methyl silicone rubber (MFQ)
• Perfluorinated propylene rubber (FFPM)
• Perfluorocarbon rubber (FFKM)
• Polyurethane (PU)

The aforementioned types of rubber may be unblended. It is also possible to use a blend, in particular in combination with one of the abovementioned types of rubber, for example an NR / BR blend or a BR / SBR blend.

Of particular importance are: EPM, EPDM, SBR, BR, CR, NR or NBR.

The usual compounding ingredients include at least one crosslinker or crosslinker system (crosslinker and accelerator). Other mixing ingredients are usually still a filler and / or a processing aid and / or a plasticizer and / or an aging inhibitor and optionally further additives (eg color pigments). In this regard, reference is made to the general state of rubber mixing technology.

Variant B

The vulcanizate is a thermoplastic vulcanizate containing at least one thermoplastic component, at least one rubber component which is at least partially cross-linked, and compounding ingredients. Thermoplastic vulcanizates are, for example, from DE 100 04 631 A1 known.

The preferred thermoplastic components are polyethylene (PE), polypropylene (PP), polystyrene, polyamide (PA) or polyester (PES).

As rubber components are in particular EPM, EPDM, SBR, BR, CR, NR or NBR, especially in cuttable design, call.

With regard to the mixture ingredients, reference is made to the above-mentioned mixture technology, in particular to the teaching according to the published patent application DE 100 04 632 A directed.

In connection with the novel material for the printing layer, it is necessary that the printing layer rests directly on a compressible layer, in contrast to one of the embodiments according to the patent specification EP 0 844 100 B1 or the published patent application DE 103 18 039 A1 according to which the printing layer has direct contact with a reinforcement layer or the printing layer is connected to the reinforcement layers via further non-compressible layers.

• Druckschicht;
• kompressible Schicht;
• Festigkeitsträgerschicht.

According to the invention, the compressible layer, which is in direct contact with the printing layer, rests directly on a reinforcing layer so that, irrespective of the number of layers, the following basic structure exists:

• Print layer;
• compressible layer;
• Strengthening support layer.

In this basic structure, further layers can follow, in particular under the aspect of further compressible layers and reinforcement layers.

The compressible layer - also called compression layer - serves to avoid a flexing process by reducing the volume in the pressure zone and to compensate for Eindrückungsunterschieden. For the compressible layer, it is crucial that it does not expand when compressed, that is, that its volume actually shrink when compressed, so that no laterally spreading distortions arise. For example, microspheres made of plastic in a rubber compound or a microporous cell structure with enclosed gas chambers (foams) can be used here. The relevant materials are in particular polyurethanes, crosslinked polyethylenes, polypropylenes, NBR, Neoprene and EPM. The modulus of elasticity is usually in the range of 1 MPa to 1000 MPa. For further details on the compressible layer, reference is made to the literature cited at the beginning, in particular to the documents EP 0 844 100 B1 and EP 2 070 717 A1 directed.

As a reinforcement layer, a textile structure, for example a woven fabric, or a film, for example a polymer film (eg polyamide film) or metal foil, can be used. In the case of a fabric having many layers and at least two reinforcement layers, it is also possible to implement a combination of a textile structure and a film or a film composite. So in the patent EP 0 844 100 B1 a six-layer sheet with three fabric layers and a film layer (polymer film or metal foil) is described.

The new multi-layered fabric in the form of a blanket or a printing plate is delivered to the customer as roll goods. This assembles the Rolled goods on a sleeve (adapter, printing cylinder) and then lasiert the print layer, combined with a subsequent cleaning. In conjunction with today's laser technologies, engraving with halftone dots of different depths and shapes can be introduced into the new printing layer from a vulcanizate. The engraving is done quickly, cleanly and without solvents. It ensures a 100% registration accuracy and reproducibility. Of great economic importance is the fact that the customer requires significantly fewer process steps when creating the printing form.

The multilayer sheet can also be supplied as a self-adhesive composite.

In the following, a comparative experiment and its results are presented in the context of a table. In each case a three-layer printing plate is compared, each with a layer sequence of printing layer, compressible layer and reinforcement layer. The printing layer consists firstly of a prior art of a photopolymer and secondly according to the teaching of the invention of a thermoplastic vulcanizate based on a peroxidically crosslinked EPDM. Test criteria are in each case the most important technical data, namely the tonal range, the color intensity and the dynamic Beistellung. <U> Table </ u> test criteria Three-layer printing plate with printing layer based on a photopolymer Three-layer printing plate with printing layer based on EPDM tonal + +++ color intensity + +++ Dynamic provision + +++

• + Standard
• ++ über Standard
• +++ weit über Standard

With regard to the evaluation of the test criteria mean:

• + Standard
• ++ over standard
• +++ far beyond standard

• Mit der neuen Druckschicht aus einem Vulkanisat tritt eine signifikante Verbesserung der Druckleistung auf.
• In diesem Zusammenhang ist es notwendig, wenn die Druckschicht direkt auf einer kompressiblen Schicht aufliegt. Diese kompressible Schicht hat wiederum einen direkten Kontakt zu einer Festigkeitsträgerschicht.
• Die Besten Ergebnisse werden erzielt bei einem thermoplastfreien Vulkanisat auf der Basis EPM, EPDM, SBR, BR, CR, NR oder NBR. Die vorgenannten Kautschukkomponenten können unverschnitten sein oder einen Verschnitt bilden, beispielsweise einen BR/SBR-Verschnitt.
• Das neue Konzept ist im Wesentlichen unabhängig von dem Werkstoff der kompressiblen Schicht und der Festigkeitsträgerschicht.
• Es lassen sich eine Vielzahl von Schichtenaufbauten unter dem Aspekt der Auslieferung als Rollenwaren realisieren, wobei das Schichtenkonzept gemäß Patentanspruch 10 oder 12 vorteilhafte Gestaltungsvarianten sind, die in Verbindung mit der Figurenbeschreibung noch etwas näher vorgestellt werden.
• Die Erstellung der Druckform auf der Grundlage einer gelaserten Druckschicht aus einem Vulkanisat ist mit weniger Verfahrensschritten verbunden als beim Arbeiten mit Photopolymeren.

With reference to this comparative experiment as well as supplementary investigations, the following must be stated:

• With the new printing layer from a vulcanizate, a significant improvement in printing performance occurs.
• In this context, it is necessary if the printing layer rests directly on a compressible layer. This compressible layer in turn has a direct contact with a reinforcement layer.
• The best results are achieved with a thermoplastic-free vulcanizate based on EPM, EPDM, SBR, BR, CR, NR or NBR. The abovementioned rubber components may be uncut or form a blend, for example a BR / SBR blend.
• The new concept is essentially independent of the material of the compressible layer and the reinforcement layer.
• It can be a variety of layer structures under the aspect of delivery as a roll goods realize, the layer concept according to claim 10 or 12 are advantageous design variants, which will be presented in more detail in connection with the figure description.
• The creation of the printing form based on a laser-printed layer of a vulcanizate involves fewer process steps than when working with photopolymers.

Fig. 1

einen Querschnitt eines dreischichtigen Flächengebildes mit einer Druckschicht aus einem Vulkanisat;

Fig. 2

einen Querschnitt eines fünfschichtigen Flächengebildes mit einer Druckschicht aus einem Vulkanisat;

Fig. 3

eine Draufsicht einer Druckschicht aus einem Vulkanisat mit Lasergravur.

The invention will now be explained by means of exemplary embodiments with reference to schematic drawings. Show it:

Fig. 1

a cross section of a three-layer sheet with a pressure layer of a Vulkanisat;

Fig. 2

a cross section of a five-layer sheet with a pressure layer of a vulcanizate;

Fig. 3

a top view of a printing layer of a vulcanizate with laser engraving.

Fig. 1 shows a three-layer sheet 1 in the form of a blanket or a printing plate with a printing layer 2 of a vulcanizate, for example based on EPDM, wherein the printing layer rests directly on a compressible layer 3, for example in the form of plastic microspheres in a rubber compound. This compressible layer then in turn has direct contact with a reinforcement layer 4, for example of a fabric.

• Druckschicht 6 aus einem Vulkanisat;
• erste kompressible Schicht 7, beispielsweise in Form von Mikrokugeln aus Kunststoff in einer Gummimischung;
• erste Festigkeitsträgerschicht 8, beispielsweise aus einem Gewebe;
• zweite kompressible Schicht 9, beispielsweise wiederum in Form von Mikrokugeln aus Kunststoff in einer Gummimischung;
• zweite Festigkeitsträgerschicht 10, beispielsweise wiederum aus einem Gewebe.

Fig. 2 shows a five-layer sheet 5 with the following layer sequence:

• Print layer 6 of a vulcanizate;
• first compressible layer 7, for example in the form of plastic microspheres in a rubber compound;
• first reinforcement layer 8, for example made of a fabric;
• second compressible layer 9, for example again in the form of plastic microspheres in a rubber compound;
• second reinforcement layer 10, for example, again from a fabric.

In a fabric according to Fig. 2 It is also possible to work with different reinforcement layers, for example by the first reinforcement layer of a fabric and the second reinforcement layer of a film, for example of a polymer film (eg polyamide film) or a metal foil, or a film composite, for example in the form of a polyamide pad -Filienverbundes, exist.

The multilayer fabrics in the embodiments according to Fig. 1 and Fig. 2 can be supplied as roll goods. The customer then carries out the laser engraving according to the specification.

Fig. 3 now shows a print layer 11 with a laser engraving 12, here in the form of the year 2005. Due to the fact that the print layer is a vulcanizate, when creating the printing form engraving with grid points under the aspect of different depths and shapes can be generated.

LIST OF REFERENCE NUMBERS (Part of the description)

1

Multilayer flat structure (blanket, printing plate)

2

print layer

3

compressible layer

4

Strengthening support layer

5

Multilayer sheet (blanket, printing plate)

6

print layer

7

first compressible layer

8th

first reinforcement layer

9

second compressible layer

10

second reinforcement layer

11

print layer

12

laser engraving

Claims (10)

1. Multilayer sheet (1, 5) in the form of a printing blanket or of a printing plate for flexographic printing and letterpress printing with:

   - a printing layer (2, 6, 11) made of a polymeric material and provided with laser engraving (12);

   - at least one compressible layer (3, 7, 9), and also

   - at least one reinforcement layer (4, 8, 10);

   where the individual layers mutually form an adherent composite and the polymeric material of the printing layer (2, 6, 11) is a vulcanizate, characterized in that the printing layer (2, 6, 11) is in direct contact with a compressible layer (3, 7) and the said compressible layer (3, 7) is in direct contact with a reinforcement layer (4, 8).
2. Multilayer sheet according to Claim 1, characterized in that the vulcanizate is a vulcanized thermoplastic-free rubber mixture comprising at least one rubber component, and also mixing ingredients.
3. Multilayer sheet according to Claim 2, characterized in that the rubber component is ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), nitrile rubber (NBR), (partially) hydrogenated nitrile rubber (HNBR), fluororubber (FKM), chloroprene rubber (CR), natural rubber (NR), styrene-butadiene rubber (SBR), isoprene rubber (IR), butyl rubber (IIR), bromobutyl rubber (BIIR), chlorobutyl rubber (CIIR), butadiene rubber (BR), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), polyepichlorohydrin (ECO), ethylene-vinyl acetate rubber (EVA), acrylate rubber (ACM), ethylene-acrylate rubber (AEM), silicone rubber (VMQ), fluorinated methylsilicone rubber (MFQ), perfluorinated propylene rubber (FFPM), perfluorocarbon rubber (FFKM), or polyurethane (PU), where the abovementioned types of rubber are used without blending or in a blend, in particular in conjunction with one of the abovementioned types of rubber.
4. Multilayer sheet according to Claim 3, characterized in that the rubber component is EPM, EPDM, SBR, BR, CR, NR or NBR.
5. Multilayer sheet according to Claim 1, characterized in that the vulcanizate is a thermoplastic vulcanizate comprising at least one thermoplastic component, at least one rubber component, which has been at least partially crosslinked, and also mixing ingredients.
6. Multilayer sheet according to Claim 5, characterized in that the thermoplastic component is polyethylene (PE), polypropylene (PP), polystyrene, polyamide (PA), or polyester (PES).
7. Multilayer sheet according to Claim 5 or 6, characterized in that the rubber component is EPM, EPDM, SBR, BR, CR, NR or NBR.
8. Multilayer sheet according to Claim 1, characterized in that the sheet (1) has three layers, and specifically in the following layer sequence:

   - printing layer (2);

   - compressible layer (3);

   - reinforcement layer (4).
9. Multilayer sheet according to any of Claims 1 to 7, characterized in that the sheet (5) has at least four layers.
10. Multilayer sheet according to Claim 9, characterized in that the sheet (5) has five layers, and specifically in the following layer sequence:

    - printing layer (6);

    - first compressible layer (7);

    - first reinforcement layer (8);

    - second compressible layer (9);

    - second reinforcement layer (10).

Images