DE10104164B4 - An article with a seal and its use in a printing machine - Google Patents

Abstract

object with a surface which to increase their Fluidtrage- and / or -aufnahmefähigkeit is microstructured enlarged and having substructures with a substructure seal, characterized in that the sealing substances are antistatic Have properties.

Description

The The present invention relates to articles and their surfaces according to the preamble of claim 1 and its use in a printing machine according to claim 7th

Such objects and their use are for example from the DE 689 10 319 T2 known.

It is common desirable, an article with a hydrophilic or, more generally, fluidphilic or liquid-loving surface provided. This is about the case when the fluid from a first to be transferred to a second location on the surface. A typical case is realized in printing machines, where Color to be transferred got to.

It has been proposed to provide the surfaces of such transferring articles with flared, sputtered or similarly applied layers, such as CrO ₂ . In these, the hydrophilicity, as far as the mechanisms are understood, results from the structuring of the surface.

It can in this case, for example, in scanning electron images, a paving effect Areas arise. Determine the rough outlines of the flatbreads themselves doing a microstructure, but in the areas where two or several pancakes on top of each other come lie, are finely substructured, so fine substructure pores have, where the pancakes are not tightly packed. The hydrophilicity is now the spongy and / or pore-like, but anyway textured surface attributed to the assumption that fluid penetrates into the pores and thus the fluid absorption capacity elevated becomes.

Problematic But, as in the printing press area, that is not pure solvent and / or pure fluid is applied, which can be completely detached, but often Pigments and the like are present. These then sit down in or in front of the pores and lead both to a deteriorating Fluidphilie as well as pollution all in all.

DE 689 10 319 T2 describes a fountain roller for an offset printing press, wherein the surface has substructures with a substructure seal.

The Object of the present invention is new to the commercial To provide application.

The solution This object is achieved by the features of claims 1 and 7. Preferred embodiments can be found in the subclaims.

proposed thus becomes first an object with a surface, which to increase your Fluid carrying and / or absorbing capacity microstructured is enlarged and having substructures with a substructure seal, thereby characterized in that the sealing substances are antistatic Have properties.

Preferably this object has an amplitude and a spatial Frequency exhibiting basic and fine structure, the basic structure in Compared to the fine structure a larger amplitude and a lower one spatial Frequency has.

Fundamental is thus the per se paradoxical realization that, although the structuring was done to the Fluidtrage- and / or absorption and / or transfer ability microstructured to enlarge the Fluid amount can be increased by repeated sealing transfer can. Nevertheless, advantages are achieved by using a substructure sealant is achieved. It was recognized that although such small capillary openings possibly closed be that but with a suitable design of the seal nevertheless in the entrance area of the capillary enough fluid to the optionally and ideally only very small and very small pores Seal can be fixed, with the smallest and smallest Pores in particular a factor of two, in particular a factor 5, particularly preferably an order of magnitude smaller than the Macro structuring can be, which, however, in turn with can be sealed.

The Microstructure does not have to be periodic, but may be stochastic and / or be formed quasi-stochastic. In particular, initially a non-smooth surface be provided, in particular with a basic structure of higher amplitude and less spatial Frequency on which a fine structure with lower amplitude and higher spatial Frequency is and / or will be established.

It is possible and preferred if the microstructure is formed by regions of flat and / or flat superimposed material. This can be achieved if the microstructure is formed by material bumping on the surface during manufacture. The microstructure can be sprayed and / or flared by Ma be formed terial, in particular by a metal oxide, in particular CrO ₂ .

The Substructure seal can have oleophobic properties and / or completely oleophobic. At the same time, the seal be hydrophilic and / or hydrophobic. Amazing here is that in particular a hydrophobic seal of a hydrophilic structure can deliver consistently better results than an unsealed one Surface.

It is also possible to adapt the surface energy of the article to the fluid and adjacent articles from or to which it is transferred. This adjustment of the surface energy can be achieved in particular by a coating of the parts involved, for example, in operation adjacent to one another. A coating composition having a very low surface energy is known, for example, from US Pat EP 0 587 667 B1 known. The main claim of this prepublished document discloses an organometallic coating composition comprising an average of from 5 to 30 fluoroaromatic perfluorinated groups bound to one or more aliphatic carbon atoms separated by at least two atoms of M. Such a coating composition has a low surface energy. If instead of some or all of the fluorine atoms z. For example, when alkyl groups are incorporated, the surface energy of the resulting composition or surfaces treated with the composition increases, and so on, the fewer fluorine atoms are exchanged. The surface energies are typically set between 10 mJ / m ² and 80 mJ / m ² , preferably between 15 mJ / m ² and 70 mJ / m ² . It is preferably ensured that the composition used for the coating is particularly low viscosity, that flows well into the pores and so can act primarily where it is desired, namely in the substructure area.

The In addition, the composition is preferably applied very dilute to the structured surface. Background is that the substructures to be sealed, as they are are only slightly polluted, even small layer thicknesses need and at the same time the thin ones Layers the sealing of only the finest pores and / or substructures enable it but not such pores and / or substructures closed they are not, because of their size easily soiled by pigment deposits or the like Therefore, no sealer need, as they permanently for Contribute fluidphilia of the object.

The sealing can be carried out with fluorinated, in particular multi-fluorinated substances. Such coating compositions can be based on polycondensates of one or more hydrolyzable compounds of at least one element M from the main groups III to V and transition groups II to IV of the periodic system, wherein at least a part of these compounds in addition to the hydrolyzable groups A also nichthydrolisierbare carbonaceous groups B and the total molar ratio of groups A to groups B in the parent monomeric starting compounds is 10: 1 to 1: 2, wherein for a given proportion of the composition, groups B are groups B 'having on average 5 to 30 fluorine atoms are bonded to one or more aliphatic carbon atoms separated by at least two atoms of M, and further wherein in a second portion of the composition, the groups B are those groups B "which are chosen to have a higher surface energy for them yields over 25 mJ / m ² , in particular more than 60 mJ / m ² . The lower value of 25 mJ / m ² differs comparatively little from that of the highly fluorinated compositional proportions, allowing fine adjustment, while the second higher value provides a wider range of adjustment possibilities. In particular, the surface energy of the second portion may also be higher, such. At 70 or 80 mJ / m ² . It should be mentioned that in the choice of the second composition proportion it is above all and primarily of importance that, on the one hand, the required high surface energy is given and, on the other hand, in the mixture with the perfluorinated first portion, a sufficiently stable and thus, in particular, good crosslinking on a substrate Composition results.

It It is envisaged that the sealant will have antistatic properties has, which particularly favors the pigment removal during transfer and / or that increases the scratch resistance is. This can be done by using suitable nanoparticles in the sealant composition be effective.

It be mentioned that in the sealant - in particular by high-frequency eddy currents heatable particles can be introduced, preferably Nanoparticles that remain in the coating. If the particles heated by high-frequency electromagnetic alternating fields, heats up the entire layer with. Thus, a curing of the composition can be achieved without having to warm up the entire object. Alternatively, the coating even with a sufficiently powerful and sufficient for achieving high temperatures ausgegege hot air blower and / or an infrared light source to be heated.

The sealer may come with a solution before which does not contain fluorosilane, which has the advantage that local micelle formation in the pores is safely avoided and the seal is improved. Instead, nanoparticles and active binding phases may be present according to the invention.

When sealing solution is proposed according to the invention a solution, contains the following components: Silica sol, silicic acid esters, which are anhydrolyzed or partially hydrolyzed and / or condensed are and / or organically modified silicic acid esters, wherein the organic Modification is effected by groups which cause coupling of the monomer enable, which later is applied to the surface properties to achieve. Anhydrolyzing, condensing, etc. of the silicic acid compound As a result, first, the pores are better closed can and second, a chemically stable connection to the subsurface, for example Chromium dioxide, as on chromed surfaces of printing presses too can be obtained.

When Nanoparticles that also contain in the sealing solution could be, can Yttrium salts or nanoparticles ITO, ATO, FTO or metal particles used in nano size become. Through these can antistatic properties are mediated. There are also other nanoparticles can be used. The reason for the use of nanoparticles is that the bulk component shrinks as it dries, resulting in penetration in the to be filled Pores would again cause cracks. Prevent the nanoparticles Cracking on shrinkage of the sealing solution serve So as a filler. This is preferred if they have a diameter of z. B. 1/10 of the typical be replenished Have pores so that they can penetrate well into these.

It is possible, too, Monomers, in particular fluorinated monomers are not based on a applied seal, but directly on eg in a Printing machine existing objects, especially rollers, anilox rollers etc .. This is possible, though many rolls of metal surfaces exhibit. causal for this, that this is possible is the fact that metal surfaces, as far as it is not is about precious metals, regularly oxidized superficially are, d. H. Oxides / hydroxides u. Like. Have. At kinetic activation (Warming) the substance to be applied and / or the surface to be coated is then enough energy to disposal, to effect a condensation. At the condensation form on the one hand, bonds between the metal surface and the monomer of and on the other hand, among the condensing monomer molecules, so that there is an at least partial cross-linking on the surface, what the consistency the forming coating of the layer produced by the monomer elevated. It is preferred that the surface is cleaned beforehand, is fat-free in particular, what with conventional fat-dissolving solvents and / or Method can be achieved.

The Monomer can be used activated or not activated. The Activation takes place by incorporation / conversion of reactive groups, which for example by adding water or the like to the monomer. Possible monomers are fluorine compounds, in particular with following properties: perfluorinated groups bonded to silicon with 2C atoms spacer distance, the use of fluorinated Si compounds has the advantage of having very durable coatings because of the fact that between Si and the superficial form existing metal hydroxide bonds and, moreover a very good three-dimensional crosslinking of the monomers takes place. It is also possible, but to use fluorinated organic compounds less durable compounds result, making a more frequent Coating and renewal of the coating is required; of the The advantage here is that the organically fluorinated compounds possibly cheaper to produce and thus the individual coating cheaper perform is what can lead to a total cost advantage.

For the fluorinated compounds, it is preferred aliphatic, long-chain, resp. to use cyclic aliphatic or aromatic compounds. It is preferable to use CF ₂ groups in the compounds because CFH groups and the like are highly toxic.

The Invention can also be used in flexographic printing.

A Antistatic coating is particularly important if Rubber rollers are coated, which are particularly sensitive to paper dust and in the presence of the same a worse printed image give. The use of a coating with antistatic properties However, it also has positive effects on other parts of a press. This applies to the same extent in particular for rolls made of or with ceramic material. It is still possible an electrostatic coating, in particular a primary sealing layer to carry out, d. H. to spray the coating electrostatically with it a particularly good penetration takes place. This improves the electrostatic Even then coating the properties of the article positively, if only and exclusively the substructures were sealed.

The required electrostatic properties Shapes of the coating can be embossed and achieved by nanoparticles / structures having groups capable of dissociation, in particular OH groups, dissociation resulting in charge separation and chargeability.

A porous Roller can preferably be coated in a moistened state. The humidification can in particular with the same solvent done as it is for the coating composition is used. The result of moistening is then that solvent into the capillaries of the porous Structures, such as superimposed material patties penetrates. Now, when the coating dries out, becomes solvent from the coating surface evaporate away. It leaves can not avoid that in the capillaries of the microstructure solvent remains; because the capillary forces are bigger as the vapor pressure of the solvent is. If the coating then for purposes of curing or heated like is, the vapor pressure of the remaining solvent in the capillaries increases so strong that steam forms. In conventional coatings can this may not escape, since the superficial drying steam-proof is. In contrast, with the coatings used with nanostructures and / or particles within the substructures in any case given sufficient porosity for evaporation, to evaporate the solvent residues to allow the capillaries without the surface of the already cured or at least hardened Coating material bursts or the seal is impaired.

In a further embodiment the object of the invention is achieved by a part of a printing machine, in particular a roller, in particular an anilox roller, comprising an article according to the invention with a surface according to the invention.

The invention is described by way of example only:
A roll of a printing machine provided with a warty chrome structure is coated with a coating according to EP 0587 667 B1 coated. The result is a pressure roller that does not need to be cleaned for the first 14 days of operation and then easy to clean for about half a year with an oil flap. This is attributed to the good transferability of the color due to the changed surface energy.

It It should be noted that with smooth rollers, so not wary coated rollers, the effect disappears comparatively quickly. So after 1700 printed copies no effect was noticeable. at a sand or shot peened, but otherwise smooth roller was it possible, to print up to 11,000 copies until the effect disappears. Both are probably up compared to the chromium-wart structure the very high abrasion of the coating in a smooth or near due to smooth roller is but not completely Understood.

Become coated not yet unused rolls, but already operated, z. B. long after a previous coating, they must getting cleaned. This cleaning is per se in the art known. It is possible, by blasting with sand, baking powder, shot peening, cryo rays, Corona rays, ultrasound, etc. Further, the can be removed from the aircraft known laser scanner can be used. For anilox rolls is due the fine cell structures also cleaning by blasting with in particular in an at least virtually closed circuit to leading nanopowder possible. The cleaned rolls can then be coated.

It be mentioned that while in the present invention with reference to printing machines and to be transferred Color has been described, corresponding benefits less required expectant cleaning also in others continuously and / or cyclically working machines result in which well-adherent, heavy transfer removable materials or handed over should be. An example of this is PVC film-producing machines in which currently on the guided by the output fluid heating rollers in large mass silicone oils need to be applied to ensure the transfer of the PVC material. Again, a coating of the invention is advantageous. further is a coating according to the invention advantageous in the band screens used there, etc.

Claims (7)

An article having a surface which is microstructured to increase its fluid carrying and / or receptivity and having substructures with a substructure seal, characterized in that the sealing substances have antistatic properties. An article according to claim 1, having an amplitude and a spatial Frequency-containing basic and fine structure, the basic structure Compared to the fine structure, a larger amplitude and a lower one spatial Frequency has. Article according to one of the preceding claims, characterized in that the microstructure by areas flat and / or flat is formed overlying material. Article according to one of the preceding claims, characterized in that the microstructure comprises a metal oxide, in particular CrO ₂ . Article according to one of the preceding claims, characterized characterized in that the substructures with fluorinated substances are sealed. Article according to the preceding claim, characterized characterized in that the substructures with multiply fluorinated substances are sealed. Part of a printing machine, in particular a roller, in particular an anilox roll comprising an article according to one of the preceding claims.