Dosing roller with elastic recesses

Abstract

The invention relates to an anilox roller (4) for a printing machine, which has recesses (3) arranged on a circumferential surface, characterized in that at least a portion of the recesses (3) has at least one reversibly compressible material.

Description

Technical Field

[0001] This invention discloses an improved dispensing method based on anilox rollers.

[0002] This invention relates to the technical field of ink application in printing presses. Background Technology

[0003] In the printing industry, various methods for applying ink to a printing mold are known. These methods include, for example, the use of anilox rollers with permanent recesses; dispensing methods using gaps; or dispensing methods performed by rollers in printing methods (such as offset printing). Each method has its own advantages and disadvantages.

[0004] Anilox rollers (RWs) are only partially emptied during dispensing. The degree of emptying depends on the emptying of the engraved recesses (especially the emptying related to the printed image). Therefore, anilox rollers typically do not operate without reaction (rückwirkungsfrei), which can lead to ghosting. This means that these anilox rollers are not completely emptied during dispensing. This also results in the need to use large-format anilox rollers (RWs) in offset printing, depending on the printing plate size, which limits the maximum economically meaningful size of the printing plate.

[0005] Furthermore, the evacuation characteristics of printing ink in anilox rollers depend on the roller temperature. Printing speed similarly affects evacuation characteristics and therefore, dosage characteristics.

[0006] A dispenseable anilox roller is known from European patent application EP 1 020 287 A2, particularly for anilox ink mechanisms in web rotary printing presses. The anilox roller has recesses for receiving various printing inks arranged on the circumferential surface of the roller. The anilox roller is characterized in that the bottom of the recesses is made of an elastic material, and there are associated chambers below the recesses that can be loaded by printing media to increase or decrease the volume of the recesses. Summary of the Invention

[0007] The objective of this invention is to provide an improved method for dispensing anilox rollers and an improved anilox roller itself, said dispensing method and said anilox roller solving the problem of insufficient evacuation.

[0008] This task is solved by an anilox roller for a printing press according to the invention, the anilox roller having recesses arranged on a circumferential surface, characterized in that at least a portion of these recesses is filled with a reversibly compressible material. In the sense of the invention, "reversibly compressible material" is understood as a material whose initial volume decreases under external pressure and whose volume substantially increases back to its original initial volume when the external pressure is removed. Such reversibly compressible material is generally elastic. Such reversibly compressible material can be wholly or partially porous, or non-porous.

[0009] Advantageous and further preferred extensions of the anilox roller according to the invention are derived from the specific embodiments and from the description and accompanying drawings.

[0010] These expansion plans include:

[0011] 1. Such reversibly compressible materials include at least one plastic, and in particular at least one elastomer.

[0012] 2. Such reversibly compressible material includes at least one vulcanizate of natural or synthetic rubber, which may also be referred to as gum.

[0013] 3. Some depression fillers, which are filled with materials that are reversibly compressible, are less compressible than other materials.

[0014] 4. Referring to the initial volume of such reversibly compressible material, the initial volume of such reversibly compressible material can preferably be reduced to less than 90% (volume), particularly preferably to less than 80% (volume), and very particularly preferably to less than 70% (volume) under pressure.

[0015] 5. Referring to the corresponding volume of the cavities, these cavities are preferably filled to at least 30% (volume), particularly preferably to at least 60% (volume), and very particularly preferably to at least 90% (volume) with a material that can be reversibly compressed.

[0016] Hereinafter, the anilox roller according to the invention is preferably manufactured by a method characterized by providing an anilox roller with hollow depressions, filling these depressions with a liquid material, and solidifying the liquid material.

[0017] Another preferred manufacturing method is characterized in that the anilox roller is coated with a reversibly compressible elastomer, particularly rubber, and that after coating, the protruding elastomer is worn away, so that at the end of the processing, only the indentation of the anilox roller still contains rubber.

[0018] Furthermore, the anilox roller according to the invention is used in a printing method of a printing press. A preferred extension of this method includes: using a highly viscous printing medium; and the pressure used to fill the depressions of the reversibly compressible material with liquid material is either static or dynamic. Attached Figure Description

[0019] Next, the invention itself, as well as structurally and / or functionally advantageous extensions thereof, will be described in more detail with reference to the accompanying drawings, based on at least one preferred embodiment. In the drawings, corresponding elements are given identical reference numerals. The drawings show:

[0020] Figure 1 The image shows the scraping process (top image) and the state after scraping (bottom image);

[0021] Figure 2 This illustrates an alternative wiping process for a cavity wiping system;

[0022] Figure 3 This shows a segment of the anilox roller surface where the diaphragm (scraping diaphragm) is used between bridging walls (middle view) or on the bridging walls (right view);

[0023] Figure 4 This illustrates the manufacturing and application scenarios of anilox rollers with reversibly compressible filler material;

[0024] Figure 5 This illustrates a scenario where an anilox roller with an irreversibly compressible mask for imaging and an reversibly compressible filling material is used.

[0025] Figure 6 This illustrates a use case for a fabric with a mask and a reversibly compressible filling material. Detailed Implementation

[0026] In a preferred embodiment, the present invention includes a dispensing roller 4 having an anilox roller structure (or gravure printing structure), wherein the recesses 3 of the anilox roller structure (or gravure printing structure) are cup-shaped grooves. The grooves (Haschur) and other features are filled with a reversibly compressible material (preferably rubber or other elastomers). The dispensing function achieved by these recesses 3 is only produced under pressure. That is, these recesses 3 are only filled with fluid 2 (preferably printing ink 2) under pressure. After the pressure is released, this reversibly compressible material relaxes, these recessed dispensing elements 4 return to their original positions, and the fluid 2 reaches the relaxed roller surface, so that the fluid 2 can be effectively output to another surface 12. This is in Figure 1 and Figure 2As shown in the figure. The anilox roller according to the invention avoids incomplete and generally non-reactive evacuation of the cup grooves, because residual ink (as shown in the figure) is removed by subsequent scraping. Figure 4 (As can be seen in the image), and thus, it is possible to achieve non-reactive or at least low-reactive dispensing. This means that there is no memory effect caused by partial emptying or partial transfer in an image-dependent manner. In particular, such anilox rollers 4 can be used in offset printing machines without having large print sizes, and without ghosting.

[0027] Another aspect of the invention relates to the manufacture of the anilox roller 4. Currently, anilox rollers 4 are typically manufactured based on chromium oxide ceramic, which is structured or engraved using a laser. For this purpose, for example, a copper layer is first engraved, and then said copper layer is electroplated with a thin chromium layer (see also the process of manufacturing gravure printing molds). Laser engraving is also possible, followed by a hard chromium coating. After the appropriate structuring, for the present invention, the anilox roller 4 is coated with an elastomer, preferably rubber. After coating, the protruding rubber material is ground away, so that at the end of the processing, only the recesses 3 still contain rubber. Thus, there exists an anilox roller 4 that is flat in itself, and the dispensing capacity of the anilox roller 4 is attributed to locally varying compressibility. The rubber in these recesses 3 is not ground away by the scraper 1, which merely rests flat on the bridging portion of the incompressible base mold (i.e., a hard surface made of ceramic or chromium).

[0028] Here, the anilox roller 4 according to the present invention is preferably used in the following method:

[0029] a) Dosing methods used in coating processes;

[0030] b) Dosing methods used in printing processes;

[0031] i) Anilox roller offset printing;

[0032] ii) Flexographic printing;

[0033] iii) A glossing method that mimics the design of flexographic printing.

[0034] Another preferred embodiment of the invention includes a method of gravure printing using an impression cylinder having a difference in compressibility related to the image. Therefore, significantly different viscosities (especially higher viscosities) of ink 2 can be achieved, as is the case in... Figure 5 As shown in the image.

[0035] The following describes an exemplary flow of the dispensing process of the anilox roller 4 according to the invention in a preferred embodiment. The anilox roller 4, as described above, is loaded under pressure with the fluid 2 to be dispensed by the cavity scraping system 6. Under pressure, depressions 3 are created, and the fluid 2 enters these depressions 3. After the pressure is released, this reversibly compressible material relaxes, and the fluid 2 reaches the surface of the anilox roller 4. If the anilox roller 4 is brought into contact with other second surfaces 12 in this state, the fluid 2 is completely or partially (“ink cracking” or “fluid cracking”) discharged onto the second surfaces 12. After the fluid transfer, the anilox roller 4 is optionally scraped without pressure to remove any remaining fluid. The process described above is then performed periodically, that is, the fluid 2 is re-dispensed under pressure into these depressions 3 by means of the cavity scraping system 6.

[0036] Here, if any residual fluid does not cause a memory effect (e.g., a memory effect caused by slight drying), the optional scraping without pressure can be omitted. Here, the pressure used to fill the recesses 3 filled with reversibly compressible material can be both static and dynamic. Static pressure refers to the pressure within the cavity-type scraper 6. Dynamic pressure refers to the pressure caused by the fluid movement between the scraper 1 and the surface.

[0037] exist Figures 1 to 6 The invention is illustrated by way of example. Figure 1 The top view shows the scraping process, and the bottom view shows the state after the scraping process. The scraping process forces the fluid / ink 2 into reversibly compressible recesses 3. After pressure is released by the dynamic pressure on the scraping blade 1, the fluid 2 reaches the surface.

[0038] Figure 2 An alternative wiping process for the cavity wiping system 6 is schematically illustrated. Additionally, overpressure dominates within the cavity, thus, in addition to the dynamic pressure caused by the wiping motion of the filling wiping element 1, the fluid / ink 2 is forced into the cup cavity by the static pressure within the cavity. After pressure relief, the fluid 2 reaches the surface.

[0039] exist Figure 3A segment of the surface of the anilox roller 4 in a preferred embodiment of the present invention is shown. The etched structure, in the form of cup grooves, grooves, etc., is filled with a reversibly compressible material. When the fluid / ink 2 is scraped onto the reversibly compressible area of ​​the die, the fluid / ink 2 is pressed into the flexible portion of the surface. After the pressure is released, the fluid / ink 2 reaches the surface of the dispensing element. Here, the use of the scraping diaphragm 7 is shown between bridging walls (middle view) or on the bridging wall (right view).

[0040] Figure 4 The illustration schematically depicts the manufacture and use of an anilox roller 4 with a reversibly compressible filler material, which receives the fluid / ink 2 when it is scraped onto the reversibly compressible area. After the scraping process, the reversibly compressible material returns to its initial position, and the fluid 2 flows out from the cup cavity onto the surface of the dispensing die 4. Cleaning is necessary / possible after printing. Then, the dispensing element 4 is ready again. Figure 4 This illustrates how the anilox cell structure 8 (the surface of the anilox roller 4) of the metering element changes within the framework of this process. Figure 4 The second figure shows a mesh cell structure 8a with compressible filler. Figure 4 The third figure shows how the anilox unit 8b is filled / colored with fluid / ink in a compressible area under pressure and then applied to the surface after scraping. After printing ( Figure 4 (Second row), fluid / ink residues may remain on the surface of the anilox cell structure 8c, requiring cleaning of the anilox cell structure if necessary. The rightmost view shows how the anilox cell structure surface 8d looks after fluid / ink transfer and possible cleaning of the fluid / ink residue 2. Then, in Figure 4 In the lower region, the result of using the anilox cell structure 8 is shown as a uniform ink layer 10 in the form of fluid 2 on the coating (or ink 2 on the printing material 9) and after reaching a stable level.

[0041] Figure 5 Similar to Figure 4 The illustration depicts a scenario where an anilox roller 4, comprising an incompressible mask for negative imaging and a reversibly compressible filler material according to the present invention, receives the ink when the fluid / ink 2 is scraped under pressure into a reversibly compressible area of ​​the printing mold. Here, in Figure 5 The manufacturing process is shown in the first three views. Here, the surface of the anilox roller is produced, and the unit of the anilox roller is recessed 11. Then, an incompressible mask material 11a is applied to this surface of the anilox roller. Figure 5The third view shows the completed mold, ready for coloring. This completed mold then has the surface of an anilox roller with a mask and compressible filler 11b. During use, in... Figure 5 The fourth view shows a colored mold 11c, which has colored areas on the compressible parts. After printing, the mold 11d returns to its state before coloring. Figure 5 The two lower views show: the printed image produced on the white substrate 12, and the appearance of the printed image 13 after reaching a stable level.

[0042] Other embodiments of the present invention include the following:

[0043] First, in principle, the anilox roller 4 can also be made of two other materials, as long as there is a difference in compressibility as required.

[0044] 1: Using two different compressible polymers (e.g., polyamide with pores and rubber as fillers or polycarbonate matrix and silicone rubber as reversibly compressible fillers).

[0045] 2: As a metal base roller, such as chrome-plated copper commonly used in gravure printing, this chrome-plated copper has rubber or silicone fillers in the recesses.

[0046] Second, another alternative is a partially porous material (such as rubber) with a closed surface layer. This improves compressibility compared to non-porous solid materials.

[0047] Third, instead of the anilox roller 4, a fabric structure 14 can also be used, similar to that used in screen printing, which is applied to the substrate, for example. The perforations of the fabric 14 correspond to the engraved portions of the anilox roller 4. Figure 6 The illustration depicts a use case for a fabric having a mask and a reversibly compressible filler material that receives the fluid / ink 2 when it is scraped onto a reversibly compressible area of ​​the printing die. Alternatively, in another embodiment, the mask can be omitted. This primarily relates to a dispensing element for surface coating applications. In this case of coating, the so-called reaching of a stable level (Leveln) is particularly important, and this process can also be promoted by heat. Figure 6 The first view in the image shows fabric 14 itself. Similar to... Figure 5 ,exist Figure 6 The second view shows fabric 14a with an incompressible mask. Then, in Figure 6 In the third view, the completed print can be seen as fabric 14b with a mask and reversibly compressible filler. When used for printing, in Figure 6 The fourth view shows a fabric 14c with a mask and a colored area on the compressible part, and... Figure 6 The right-hand view also shows the impression as fabric 14d without ink after printing. Similar to... Figure 5 ,exist Figure 6 The two lower views show: the printed image produced on the white substrate 12, and the appearance of the printed image 13 after reaching a stable level.

[0048] Fourth, for rotating fabrics filled with reversible elastic material and hollow internally, dispensing or imaging functions can be achieved based on a similar principle of temporary compression of the elastic filling material. Unlike anilox roller 4 or gravure printing molds, in the case of a closed screen, negative pressure or overpressure can be achieved from the inside in a simple manner. The filling process performed by the squeegee system 6 can thus be achieved without the pressure chamber squeegee 1. During filling, negative pressure is generated inside the screen, thereby pulling the elastic filling material inward and creating deeper areas between the fabric openings, which are filled with ink 2, etc., when squeegeed. After filling, the internal pressure can be increased, thereby allowing the fluid 2 located in the recess 3 to reach the surface of the fabric. Here, the fluid 2 can even flow ("reach a stable level") and be output as a layer that can be easily dispensed and transferred to the contacting surface 12. If necessary, the fluid 2 can also be heat-treated before transfer to, for example, to improve flow, to form a uniform thin film layer before the fluid layer is transferred, or to partially dry it, or both.

[0049] If the rotating fabric systems 14, 14a, 14b, and 14c are used as printing molds, this can be achieved as follows. The fabrics 14, 14a, 14b, and 14c cover two types of materials. On one hand, there is a less compressible or incompressible material 14a (which constitutes the mask 14b), and on the other hand, there is a reversibly compressible material. The areas of this reversibly compressible material can be supplied with fluid / ink 2 under pressure (as explained above), while the mask areas of the less compressible mask materials 14a and 14b are not. Thus, there exists a printing mold that functions similarly to a screen printing mold. However, this does not relate to a screen printing method like screen printing, but rather more precisely to a planographic printing method employing a dynamic gravure-like filling method.

[0050] Fifth, if a higher viscosity ink is desired, or if better emptying of the cups is desired in the case of common thin ink 2, the method according to the invention can also be used in gravure printing (i.e., in the printing die, relative to the dispensing die). Preferably, this is achieved by a so-called electrostatic printing aid, in which the cups are better emptied by an electrostatic field.

[0051] Sixth, this method can also be used in pad printing. As is well known, a flat gravure printing die is periodically filled using a scraping system 6. The pad printing pad picks up ink 2 from the gravure printing die and transfers it to the substrate or body.

[0052] List of reference numerals

[0053] 1. Scraping blade

[0054] 2. Fluid / Ink

[0055] 3. Reversibly compressible depressions

[0056] 4. Anilox Roller

[0057] 5. Fluid / Ink Reserves

[0058] 6. Cavity-type scraping system with filling and closing scraping elements

[0059] 7. Scraping membrane

[0060] 8. Metering element's grid cell structure

[0061] 8a has a mesh-like unit structure with reversibly compressible filler.

[0062] 8b Mesh unit structure filled with fluid / ink

[0063] 8c has an isometric cell structure with ink residue after printing.

[0064] 8d Mesh cell structure after fluid / ink transfer and cleaning of ink residue

[0065] 9. Printing substrates with fluid / ink properties

[0066] 10 Uniform ink layer

[0067] 11. The surface of the anilox roller has recessed units.

[0068] 11a Anilox roller with a surface of incompressible mask material

[0069] 11b Anilox roller with a mask and a reversibly compressible filler surface.

[0070] 11c Colored printing mold (anilox roller)

[0071] 11d The printing mold after printing

[0072] 12 Printed images on a white substrate

[0073] 13. Printed images on the substrate after reaching a stable level.

[0074] 14. Fabric with anilox roller, having recessed units

[0075] 14a anilox roller fabric with incompressible mask material

[0076] 14b anilox roller fabric with a mask and reversibly compressible filler.

[0077] 14c fabric, having a mask and dyed areas in reversibly compressible regions.

Claims

1. An anilox roller (4) for a printing press, the anilox roller having recesses (3) arranged on a circumferential surface, wherein, The depression is formed of a hard, incompressible material. Its features are, At least a portion of the recesses (3) are filled with at least one reversibly compressible material, wherein, with reference to the volume of the corresponding empty recesses, these recesses are each filled to at least 90% (volume) with the at least one reversibly compressible material and the at least one reversibly compressible material covers the bottom of the corresponding empty recesses, wherein the recesses (3) filled with the at least one reversibly compressible material are filled with fluid (2) under pressure when scraped by a scraper placed flat on the hard surface of a bridging portion made of incompressible material, the fluid (2) causes the at least one reversibly compressible material located in the recesses (3) to be recessed, and under the pressure unloading state after scraping by the scraper, the at least one reversibly compressible material relaxes so that the recessed at least one reversibly compressible material returns to its original position and the fluid (2) is located on the roller surface of the anilox roller (4), so that the recesses (3) are emptied when the fluid (2) is transferred.

2. The anilox roller (4) according to claim 1. in, The at least one reversibly compressible material includes at least one type of plastic.

3. The anilox roller (4) according to claim 1. The at least one reversibly compressible material includes at least one elastomer.

4. The anilox roller (4) according to any one of claims 1 to 3. in, The at least one reversibly compressible material includes at least one vulcanizate of natural rubber or synthetic rubber.

5. The anilox roller (4) according to any one of claims 1 to 3. in, Compared to materials that fill other depressions, at least some of the depressions (3) filled with the at least one reversibly compressible material are filled with materials that are less reversibly compressible.

6. The anilox roller (4) according to any one of claims 1 to 3. in, Referring to the initial volume of the at least one reversibly compressible material, the volume of the at least one reversibly compressible material can be reduced to less than 90% (volume) under pressure.

7. The anilox roller (4) according to any one of claims 1 to 3. in, Referring to the initial volume of the at least one reversibly compressible material, the volume of the at least one reversibly compressible material can be reduced to less than 80% (volume) under pressure.

8. The anilox roller (4) according to any one of claims 1 to 3 above. in, Referring to the initial volume of the at least one reversibly compressible material, the volume of the at least one reversibly compressible material can be reduced to less than 70% (volume) under pressure.

9. The anilox roller (4) according to any one of claims 1 to 3. in, The at least one reversibly compressible material is at least partially porous.

10. A method for manufacturing an anilox roller (4) according to any one of claims 1 to 9, in, Provide an anilox roller (4) with hollow recesses (3). The depression (3) is filled with liquid material, and The liquid material is solidified to form at least one reversibly compressible material.

11. A method for manufacturing the anilox roller (4) according to any one of claims 1 to 9, in, The anilox roller (4) is coated with at least one reversibly compressible material, and After the coating is applied, the at least one reversibly compressible material protruding from the recess (3) is removed, so that only the recess (3) contains the at least one reversibly compressible material.

12. The method according to claim 11, The at least one reversibly compressible material is at least one elastomer.

13. A printing method in which an anilox roller (4) according to any one of claims 1 to 9 is used.

14. The printing method according to claim 13, wherein, Use high-viscosity printing media.

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