EP1396350B1 - Element contacting the matter to be printed and having a colour repulsive coating, coating process thereof - Google Patents

Abstract

The print material contacting element has an ink-repellent coating on a surface of a micro-structured carrier in the form of at least one derivative of an amphiphile organic compound whose polar region has an acidic character. The carrier is metallic with a native oxidized surface. The carrier has at least one material from the group including titanium, zirconium, molybdenum, nickel, copper, aluminum, chromium, iron, silver and gold. AN Independent claim is also included for the following: (a) a method of coating a surface of a micro-structured carrier of a print material contacting element.

Description

The invention relates to a printing material contacting element with an ink-repellent coating on a surface of a microstructured support. Furthermore, the invention relates to a method for coating a surface of a microstructured carrier of a printing material contacting element.

A printing material is contacted on its way through a printing material processing machine of various elements, such as cylinders, grippers, conveyor belts, transport rollers, transfer drums, stops, guides or the like. These contacts take place for various reasons: For example, the position or the state of motion of the printing material should be fixed, or the speed of the printing material along the way should be accelerated or decelerated, or at least part of the surface of the printing material should be pressed against a surface. Due to the listed or due to other diverse purposes, it may be necessary to contact the substrate at a location or on a part of its surface on which or at which ink, especially recently applied ink is located. Furthermore, due to the geometry or the mode of operation of the printing material processing machine, a printing material contacting element at the location or on the surface, with which it touches a substrate at a time, at a different time with other elements, which print, especially fresh ink wear , get in touch. It is therefore necessary to prevent ink from being deposited at the contacting site or surface of the substrate-contacting element.

The problem presented is particularly relevant for perfecting cylinders in printing units of printing material processing machines. Due to the force of a perfecting cylinder (also counter-pressure cylinder) is the substrate against a plate cylinder in direct planographic printing or against a Blanket cylinder (also transfer cylinder) pressed in indirect planographic printing. In particular, the planographic printing process may be an offset printing process or a waterless offset printing process. The perfecting cylinder contacts the substrate at least in the printing gap of the printing forme cylinder or blanket cylinder side facing away. This opposite side may already be color-bearing, for example, if it has been printed in an upstream along the way of the substrate by the printing material processing machine upstream printing unit. This situation occurs in particular in the so-called perfecting in sheet-fed printing presses. Furthermore, even the perfecting cylinder with the printing form cylinder or blanket cylinder, which optionally ink leads, are in contact when no substrate is in the nip.

In the document GB 1,412,709 For example, a roller having an elastic surface for applying toner to glass, paper or plastic is described. The roller has a cylindrical core of a non-water swelling material, for example metal, and a gel coating. In order to change the swelling capacity or wetting behavior of the roller, the roller surface may be treated with a chemical reagent. In this case, in the swollen polymer of the gel coating, carboxyl groups can be converted into hydroxam groups by, for example, first producing COCl groups by reaction with thionyl chloride, which are then reacted with hydroxylamine.

A number of concepts have already been presented as to how surfaces of printed-material-contacting elements should be designed so that neither the printed-material-contacting elements nor the printing substrates themselves smear with printing ink. In the introductory part of the description of the document DE 101 15 876 A1 a variety of different approaches are discussed. In a group of approaches, which include, for example, chromium-plated nickel structures, spherical or convex convex and concave surface elements or granular aluminum, an influence on the microroughness of the surface of the printing material contacting element is monitored. In the approach according to the technical teaching of the document DE 101 15 876 A1 Materials are used which are known in the production of printing plates. By means of a photocatalytic reaction, these materials can be brought into a highly hydrophilic and thus color-repellent state. Examples of such materials are oxides of titanium or oxides of zirconium.

In the document DE 199 14 136 A1 a dirt-repellent surface is addressed for machine parts of a printing press. For this purpose, the surface is microstructured and provided with a coating which has a self-cleaning ability by the adhesion forces between the surface and dirt particles are reduced.

The document DE 100 63 171 A1 discloses a jacket profile of a paper-carrying cylinder in a printing press, for example a perfecting cylinder. The cylinder, in particular with a chrome surface, has evenly distributed elevations with a wear-inhibiting surface coating with a surface energy of less than 50 mN / m.

A microstructured surface of a printed-material-contacting element, in particular a reverse-pressure cylinder, with low surface energy, and thus low adhesion for printing ink, can also be represented by a plasma-sprayed aluminum oxide layer provided with a silicone coating.

An even lower surface energy, and thus an even lower adhesion for printing ink, have Perfluororganylgruppen, in particular perfluoroalkyl groups, (teflon-like) on. For example, from the document US 6,325,490 B1 It is known to provide surfaces of inkjet nozzles with teflon-type coatings by coating with self-assembling monolayer (SAM) -forming organyl thiols (R-SH). The thiols can be substituted with fluoroalkyl groups.

While it is intended, on the one hand, to prevent a printing material-contacting element from being deposited at the contacting point or surface of the printing material-contacting element, on the other hand it must be ensured that the printing material contacted by the element does not slip. This aspect can be found in the technical teaching on the coating with Organylthiolen according to the document US 6,325,490 B1 no consideration.

In general, the concepts described for the coating of printing material contacting elements are relatively expensive. If a paint repellent surface is worn, it is necessary to replace the surface, ie. H. to remove or remove the worn printed material processing element from the printing material processing machine and to use a replacement element.

The object of the present invention is to provide a printed-material-contacting element whose surface is ink-repellent, but non-slip for the printing substrate, and to provide a method of how such a surface can be produced in a simple manner.

This object is achieved according to the invention by a printed-material-contacting element having the features according to claim 1 and a method for coating a surface of a microstructured support of a printed-material-contacting element solved according to claim 9. Advantageous developments of the invention are characterized in the independent and dependent claims.

A printed material contacting element according to the invention has an ink-repellent coating on a surface of a microstructured support, wherein the ink-repellent coating comprises at least one derivative of an amphiphilic organic compound whose polar region has an acid-like character. The derivative of an amphiphilic organic compound is capable of forming a layer on the surface of the support without filling or filling up the microstructure of the support. In other words, by means of the derivative of an amphiphilic organic compound, nanostructuring of the surface of the microstructured support can be carried out without leveling the microstructure. The inventive concept includes the combination of the properties of a microstructured surface for printing material fixing with the properties of the (nanostructurally acting) ink-repellent coating by said derivatives.

The printing material contacting element may be a cylinder (preferred), a gripper, a gripper support surface, a conveyor belt, a transport roller, a transfer drum, a stop, a guide or the like. The microstructured support, which forms part of the printed material-contacting element, can have a hilly or dome-shaped structure on a microscopic scale (micrometer range). The microstructured support may have small peaks on a microscopic scale, uniformly (preferably) or unevenly distributed in a relatively smooth plane. Due to the microstructure, a printing material lying on the surface is provided on a smooth lower surface with a low percentage of support, so that a printing material can rest in a non-slip manner at a few elevated points. The derivative of an amphiphilic organic compound can form a self-assembling monolayer (SAM) on the microstructured support. It is also possible to use several derivatives of an amphiphilic organic compound or a plurality of derivatives of a plurality of amphiphilic organic compounds which can also together form a self-assembling monolayer.

The derivative of an amphiphilic organic compound may be a mono- or polysubstituted amphiphilic organic compound (having one or more different substituents). The amphiphilic organic compound may be a surfactant-like compound. The amphiphilic organic compound may be an inorganic or organic acid substituted with an aliphatic or aromatic (nonpolar) region and containing at least one element of IV, V or VI. Main group of the Periodic Table, in particular carbon (c), phosphorus (P), sulfur (S) or nitrogen (N), having. The radical may be an unsubstituted or substituted aliphatic or an unsubstituted or substituted aromatic. The remainder, the non-polar region, may in particular have a carbon chain, wherein the number of carbons is greater than or equal to 12 and less than or equal to 25. The amphiphilic organic compound, the polar region of which has an acidic character, can in representative embodiments of the reusable printing form according to the invention be a hydroxamic acid derivative {RC (O) -NH-OH} or a phosphonic acid derivative {RP (O) - (OH) 2}, in particular Derivative of n-heptadecane hydroxamic acid {CH3- (CH2) 16-C (O) -NH-OH} or a derivative of n-octadecane phosphonic acid {CH3- (CH2) 17-P (O) - (OH) 2 }, be. The derivatives of the amphiphilic organic compound may have substituents of the following amount: fluoro (F), bromo (Br), chloro (Cl), hydroxyl, benzyl, phenyl. In an advantageous embodiment, the derivative of an amphiphilic organic compound in its non-polar region is substituted in such a way that it is both color-repellent (oleophobic) and water-repellent (hydrophobic). In a preferred embodiment, the derivative of an amphiphilic organic compound is fluorinated in its non-polar region.

The microstructured support of the printing material-contacting element is in an advantageous embodiment metallic with a natively oxidized surface. The support preferably comprises at least one of titanium (Ti), zirconium (Zr), molybdenum (Mo), nickel (Ni), copper (Cu), aluminum (Al), chromium (Cr), iron (Fe), Silver (Ar) and Gold (Au) on. The support materials can be prepared and microstructured in current industrial production processes. Long-chain alkane hydroxamic acids and Alkanphosphonsäuren form on natively oxidized surfaces self-assembling monolayers, see for example JP Folkers et al. "Self-Assembled Monolayers of Long-Chain Hydroxamic Acids on the Native Oxides of Metals", Langmuir 1995, vol. 11, pages 813-824 , In the document Langmuir 1995, vol. 11, pages 813-824 by JP Folkers et al. Among other things, the synthesis of some hydroxamic acids, the preparation of natively oxidized surfaces as supports or substrates and the measurement of contact angles with respect to water are described. The content of this document Langmuir 1995, 11, 813-824 is incorporated by reference in the present disclosure of the printed material contacting element according to the invention.

Advantageously, a reliably reproducible behavior with respect to the printing material guide and the deposition of ink on the surface of the printing material contacting element is achieved. With the help of hydroxamic acid derivatives or phosphonic acid derivatives, it is possible to produce reproducibly defined ink-repellent metal oxide surfaces whose contact angles, measured against water, are greater than 90 degrees.

In a preferred embodiment, the printed-material-contacting element is an opposing printing cylinder or forms part of the surface of an offset printing cylinder.

The printing material contacting element according to the invention can be used in a printing material processing machine, in particular in a printing press. A printing material processing machine according to the invention is therefore characterized by at least one printing material contacting element. The sheet processing machine, in particular printing press, can be sheet processing or web processing. A sheet-processing printing press, in particular perfecting press, can have a feeder, a number of printing units and a boom. Typical substrates are paper, cardboard, paperboard, organic polymer film or the like. The printing material may be arcuate or web-shaped. A printing machine according to the invention can print using a direct or indirect planographic printing method (offset printing method).

In the context of the inventive idea is also a method for coating a surface of a microstructured support of a printing material contacting element. In other words, the inventive concept also includes the provision of a way in which a substrate-contacting element can be coated in a color-repellent manner with a microstructured carrier.

The inventive method for coating is characterized in that a quantity of substance which comprises at least one derivative of an amphiphilic organic compound whose polar region has an acid-like character is applied by treating the surface with an aqueous or alcoholic solution of the amount of substance on the surface ,

In the method according to the invention for coating a surface of a microstructured support of a printed material contacting element, the treated surface can be cleaned with an organic solvent, in particular an aqueous or alcoholic solution, preferably ethanol, in which non-adherent parts of the substance are soluble. In addition, the treated surface can be dried with an anhydrous process gas, such as nitrogen or dry air.

In a further development of the method according to the invention for coating a surface of a microstructured support of a printing material contacting element, the surface of the microstructured support is pre-cleaned by wetting the surface with an organic, in particular alcoholic, cleaning solution before treatment with the aqueous or alcoholic solution. Furthermore, in a further development of the method, the surface can be conditioned by irradiation, in particular with infrared, visible or ultraviolet light, before treatment with the alcoholic solution of the amount of substance.

In a preferred embodiment, the method for coating a surface of a microstructured carrier of a printing material contacting element in a printing material processing machine, in particular a printing machine, performed. With the method according to the invention, a simple way is provided to cure signs of wear of the ink-repellent surface. The coating can be carried out within the printing material processing machine.

In a particularly advantageous preferred embodiment, it is checked in the method according to the invention whether the ink-repellent property of the printing material-contacting element is sufficient or not, and a coating is carried out as a function of the result of the verification. If signs of wear deteriorate the color-rejection properties or the substrate-guiding properties, a new coating of the surface of the microstructured carrier may be made.

The process according to the invention makes it possible to apply repeatedly, renewing a coating of at least one derivative of an amphiphilic organic compound whose polar region has an acidic character, in particular hydroxamic acid derivatives or phosphonic acid derivatives, surface-microstructured substrates of contact-material-contacting elements.

Figur 1

eine vorteilhafte Ausführungsform des erfindungsgemäßen Verfahrens zur Beschichtung eines bedruckstoffkontaktierenden Elements, und

Figur 2

eine schematische Darstellung einer Druckmaschine mit einem Widerdruckzylinder, der mit einer farbabweisenden Beschichtung versehen ist, als vorteilhafte Ausführungsform eines erfindungsgemäßen bedruckstoffkontaktierenden Elements.

Further advantages and advantageous embodiments and developments of the invention will be described with reference to the following figures and their descriptions. It shows in detail:

FIG. 1

an advantageous embodiment of the method according to the invention for coating a printing material contacting element, and

FIG. 2

a schematic representation of a printing machine with a perfecting cylinder, which provided with a color-repellent coating is, as an advantageous embodiment of a printing material contacting element according to the invention.

FIG. 1 shows, in the form of a flow chart, an advantageous embodiment of the method according to the invention for coating a printing material-contacting element, as it can, in particular, also take place within a printing material-processing machine. The surface of the microstructured support in this embodiment is a natively oxidized metal surface, also referred to in this context as the metal oxide surface. Without restricting the general public with regard to the derivatives of amphiphilic organic compounds and with regard to the metal oxide surfaces, an advantageous embodiment of a method according to the invention for coating on the basis of a natively oxidized titanium surface and based on a derivative of n-octadecane-phosphonic acid is exemplified.

The metal oxide surface is first prepurified. A pre-cleaning 10 may comprise the step of rinsing with acetone, ethanol, isopropanol, ethyl acetate or other suitable organic solvent (also in aqueous or alcoholic solution). One purpose is in particular the degreasing of the surface.

The pre-cleaned metal oxide surface of the printing material contacting element is subsequently conditioned. Conditioning 12 is performed by irradiating the surface with light of suitable wavelength, intensity and illumination duration for the subsequent coating step.

The application of a quantity of substance which comprises at least one derivative of n-octadecane-phosphonic acid is carried out as follows: The titanium surface is wetted with a solution, the above-mentioned compounds in suitable concentration, close to the saturation limit, preferably in the concentration 1 μmol / l , contains. The titanium surface is exposed to a 1mM ethanolic solution of the derivative of n-octadecane phosphonic acid (stearic phosphonic acid) at room temperature for about 5 minutes.

Purification 16 of the treated titanium surface is effected by rinsing with an organic solvent, an aqueous or alcoholic solution, such as acetone, ethanol (preferred), isopropanol, ethyl acetate, or other suitable organic solvent which removes the non-adherent portions of the amount of the n-containing material. Octadecane phosphonic acid derivative solution removed.

Drying 18 of the cleaned, treated titanium surface is completely achieved with an anhydrous, a so-called dry process gas, here nitrogen.

A check 110 as to whether or not the ink-repelling property of the substrate-contacting element is sufficient can be made directly on the surface of the microstructured support or indirectly by inspecting the surface of the printing material. If signs of wear of the ink-repellent coating occur or are detected, the coating process can be repeated in whole or in part for the affected parts of the surface. Due to the simple substeps of the method according to the invention and its advantageous developments, a coating or recoating can be carried out in a printing material processing machine.

Figure 2 is a schematic representation of a printing machine with a perfecting cylinder, which is provided with a color-repellent coating, as an advantageous embodiment of a printed-material-contacting element according to the invention.

Sectionally is shown by a printing material processing machine, here printing press 20, a printing unit 22 with a printing form cylinder 24, a blanket cylinder 26 and a back pressure cylinder 28 according to the invention. The counterpressure cylinder 28 has an ink-repellent coating 30 with at least one derivative of an amphiphilic organic compound whose polar region has an acid-like character has, on a microstructured support 32. The printing material 34, here arcuate, is moved by the printing press 20 (printing material processing machine) along a path 36. The printing material 34 passes through the pressure gap formed by the blanket cylinder 26 and the counterpressure cylinder 28. The path 36 partially wraps around a first upstream sheet guiding cylinder 38, a second downstream sheet guiding cylinder 40 and a third downstream sheet guiding cylinder 42. The printing press 20 has a printing unit 22 upstream printing unit 44 and a printing unit 46 downstream printing unit 46, which in this representation not further are detailed, but the printing unit 22 are executed accordingly.

Without restricting the general configuration of a printing material processing machine 20 according to the invention, in the context of FIG. 2, the printing unit 22 is the first counterpressure of the printing press 20. In other words, the upstream printing unit 46 and optionally further upstream printing units of the printing press 20 (not shown here) print the page (FIG. Perfecting page) of the printing material 34, which comes into contact with the surface of the reversing cylinder 28, while the printing unit 22, the other side (reverse side) of the printing substrate 34 printed. On the individual cylinder partially encircling path 36 for adjacent cylinders are the straight printing side and the back pressure side of the substrate 34 alternately outside and inside of the periphery of the substrate carrying or leading the cylinder, so that, for example, the second, downstream sheet guiding cylinder 40, the back pressure side of the printing material 34 outside and is accessible for inspection. The printing unit 22, for the purpose of the automatic indirect examination, whether the ink-repellent property of the perfecting cylinder 28 is sufficient or not, on a detection device 48, which allows a visual examination of whether the printed image on the substrate 34 has been smeared or dirty. It is immediately clear to the person skilled in the art that, alternatively, a machine operator can carry out an indirect check by means of visual inspection of the printed image. The recorded measurement data are fed to a checking device 50, in which a desired value-actual value comparison is carried out, so that a decision as to whether a complete or partial Recoating is to be made or not, can be taken as soon as a threshold value of a measure for the deviation of the setpoint and actual values is exceeded. The printing unit 22 has a coating device 52, with which a complete or partial coating of the microstructured support 32 of the perfecting cylinder 28 can be made without the perfecting cylinder 28 has to be removed from the printing unit 22. The individual points or positions on the two-dimensional surface of the impression cylinder 28 can be achieved due to the rotation of the cylinder about its axis of symmetry and by translation of the coating device 52 parallel to the axis of symmetry of the cylinder. The coating device 52 is designed such that it can perform the individual steps of the method according to the invention or its advantageous developments. The coating device 52 may be actuated by the machine operator as needed, or the inspection device 50 controls the coating device 52 and the perfecting cylinder 28 at positions where a reverse coating appears necessary.

In summary, it can be stated that both the production of an ink-repellent surface of a printing material-contacting element with reliably reproducible behavior with respect to the printing material guide and the renewal of a worn ink-repellent surface can be carried out simply with the method according to the invention. The application of above-described derivatives of an amphiphilic organic compound, the polar region of which has an acidic character, within a period of a few minutes is sufficient to achieve a sufficiently strong color repellency of an opposing surface, ie surface of a perfecting cylinder, for a lithographic offset printing process. The cyclic process in the described embodiment of the inventive method according to FIG. 1 can be carried out within 30 minutes. The process according to the invention makes it possible to set metal oxide surfaces, as produced in conventional industrial production processes, in a color-repelling manner. The renewal of worn areas of the ink-repellent surface can be repeated made and, particularly advantageous to be made within a printing material processing machine.

LIST OF REFERENCE NUMBERS

10

precleaning

12

conditioning step

14

application step

16

cleaning step

18

drying step

110

Verification step

112

Repeat the coating process

20

printing material processing machine

22

printing unit

24

Plate cylinder

26

Blanket cylinder

28

Resist pressure cylinder

30

color-repellent coating

32

carrier

34

substrate

36

Way of the substrate through the printing material processing machine

38

first sheet guiding cylinder

40

second sheet guiding cylinder

42

third sheet guiding cylinder

44

upstream printing unit

46

downstream printing unit

48

detection device

50

Checking device

52

coater

Claims (15)

1. Print material-contacting element having an ink-repellent coating (30) on a surface of a micro-structured carrier (32),
   characterized in
   that the ink-repellent coating (30) has at least one derivative of an amphiphilic organic compound whose polar region has an acidic character.
2. Print material-contacting element according to Claim 1,
   characterized in
   that the carrier (32) is metallic with a natively oxidized surface.
3. Print material-contacting element according to Claim 1 or 2,
   characterized in
   that the carrier (32) has at least one substance from the group titanium, zirconium, molybdenum, nickel, copper, aluminium, chromium, iron, silver, and gold.
4. Print material-contacting element according to Claim 1, 2, or 3,
   characterized in
   that the derivative of an amphiphilic organic compound is a hydroxamic acid derivative or a phosphonic acid derivative.
5. Print material-contacting element according to any one of the preceding claims,
   characterized in
   that the derivative of an amphiphilic organic compound is substituted in its nonpolar region in such a way that it is both ink-repellent (oleophobic) and water-repellent (hydrophobic).
6. Print material-contacting element according to any one of the preceding claims,
   characterized in
   that the derivative of an amphiphilic organic compound is fluorinated in its nonpolar region.
7. Print material-contacting element according to any one of the preceding claims,
   characterized in
   that the print material-contacting element is an impression cylinder (28) or a part of the surface of an impression cylinder (28).
8. Print material-processing machine (20), in particular printing press,
   characterized by
   at least one print-material contacting element according to any one of the preceding claims.
9. Method of coating a surface of a micro-structured carrier (32) of a print material-contacting element,
   characterized by
   applying (14) a quantity of substance comprising at least one derivative of an amphiphilic organic compound whose polar region has an acidic character by treating the surface with an aqueous or alcoholic solution of the quantity of substance.
10. Method of coating a surface of a micro-structured carrier of a print material-contacting element according to claim 9,
    characterized by
    cleaning (16) of the treated surface with an organic solvent in which non-adherent parts of the quantity of substance are soluble.
11. Method of coating a surface of a micro-structured carrier of a print material-contacting element according to Claim 9 or 10,
    characterized by
    drying (18) the treated surface with an anhydrous process gas.
12. Method of coating a surface of a micro-structured carrier of a print material-contacting element according to any one of Claims 9 to 11,
    characterized by
    pre-cleaning (10) the surface of the micro-structured carrier before treatment with the aqueous or alcoholic solution of the quantity of substance by wetting the surface with an organic solvent.
13. Method of coating a surface of a micro-structured carrier of a print material-contacting element according to any one of Claims 9 to 12,
    characterized by
    conditioning (12) the surface before treatment with the alcoholic solution of the quantity of substance by irradiation.
14. Method of coating a surface of a micro-structured carrier of a print material-contacting element according to any one of Claims 9 to 13,
    characterized by
    carrying out the method in a print material-processing machine (20).
15. Method of coating a surface of a micro-structured carrier of a print material-contacting element according to any one of Claims 9 to 14,
    characterized by
    inspecting (110) as to whether the ink-repellent property of the print material-contacting element is sufficient or not, and carrying out a coating operation depending on the result of the inspection.

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