EP1657076A1 - Apparatus for transferring fountain solution and/or printing materials in printing machines - Google Patents

Abstract

Rubber cover for rollers in printing or laminating machines has a fluoroelastomer coating with a thickness of up to 100 mu m and a roughness of up to 1 mu m. Independent claims are also included for: (1) roller with a rubber cover as above; (2) printing machine with a roller or rubber cover as above; (3) producing a rubber cover as above by applying the fluoroelastomer and curing it and optionally repeating the application and curing steps until the desired coating thickness is attained.

Description

The invention relates to a roller or a blanket for a printing press with a cover of an elastomeric material having an outer surface as dampening and / or Verpressmittelübertragungseinrichtung for printing presses for the direct or indirect transfer of a moist and / or Verdruckmittels on a print carrier and the use of a Such roll or blanket and a printing press with such a roller or blanket (also commonly called blanket).

Such rolls or blankets for printing presses are used for example in offset printing. The printing means, for example a conventional printing ink, is in this case transferred from a reservoir via an inking unit to a printing plate on which the respective image is usually applied by a photomechanical method. The imaged areas of the printing plate take on the color, so that the printed image can be transferred to a blanket, which is also mounted on a cylinder. From the blanket, the ink is transferred to the respective print carrier, ie the material to be printed such as a paper web, a film or other object. At the same time the printing plate is subjected to a dampening solution, which is brought from a reservoir through a fountain solution. The fountain solution occupies the non-imaged areas of the printing plate, so that they do not accept printing ink, whereby the printed image is formed. The dampening solution is usually water, which Additives such as alcohols or other additives may have. Dampening and inking in this case each consist of a plurality of rollers, some rollers with an elastomeric reference against rollers with metallic, ceramic or plastic surface work to homogenize in the nip (Nipp) the Verdruckmittel or dampening solution, process in a uniform layer and ultimately to transfer to the pressure plate and the blanket.

The rollers with elastomeric cover must meet a variety of requirements, in particular defined mechanical properties such as hardness, wettability with the Verpressmittel or dampening solution, mechanical and chemical resistance, abrasion resistance, good cleanability and the like.

Special problems also prepares a defined transfer of colorant and dampening solution from the respective colorant and dampening solution reservoir via the respective inking and dampening unit to the printing cylinder. Thus, it has been found that variously no defined transfer of dampening solution and / or Verpressmittel takes place on the impression cylinder and ultimately on the blanket cylinder, which is referred to as "over-emulsification" of the colorant-dampening solution emulsion, ie it is too much dampening solution, especially water , incorporated in the Verdruckmitttel. This has the consequence that ultimately on the impression cylinder as well as on the blanket occupied by ink or dampening areas are not exactly separated from each other and thus on the printed substrate such as a paper web blurred contours, streaks or the like print quality degrading phenomena occur. The "over-emulsification" is partly attributed to fluctuating process conditions of the printing process, such as, for example, climatic or temperature fluctuations in the printing unit, which, however, are difficult to determine and reproducible with regard to their process parameters. There is thus one Need to improve the print quality and to enable a print result that remains very constant over time.

Furthermore, known rolls have various drawbacks in terms of back-spinning performance, i. the Verdruckmittel is not optimally transferred to the next following roll in the nip but returned to the roller. This ultimately leads to an undesirable distribution of the color and can also lead to an undesirable transfer of the color in the dampening unit. In a color change, the original color of the roller or the blanket can also be slightly accepted and transferred to the subsequent printing unit, which can lead to undesirable color deviations. These problems are also not yet solved satisfactorily. Furthermore, it is necessary to further improve the back-gap behavior of the rolls.

Furthermore, it is desirable, starting from rolls with incorporated into the elastomeric roll cover excipients such as fluorinated polyolefins to improve the long-term stability of the roller and thus the life of the printing machine and the maintenance of the same on.

Further, it should be noted that the rolls are subjected to wear in printing machines having an elastomeric covering, which results in a change in the surface properties of the roll or blanket, such as roughness and changing wetting properties that change over long periods of time opposite the Verdruckmittel or dampening solution. This makes it necessary to replace the roller cover at certain intervals and to cover the roller core with a new reference. This leads to downtime and is also costly because the cover completely remove and the roll cover is completely rebuild.

The invention is therefore based on the object to provide a fountain solution and / or Verdruckmittelübertragungseinrichtung in the form of a roller or a blanket for printing machines, which solves the above problems, especially over long periods even with changing process conditions such as climatic or temperature fluctuations, a virtually optimal Print result allows, in particular also in terms of color quality in multi-color printing, which has excellent Rückspaltverhalten, a significantly increased lifespan with unchanged properties especially in terms of hardness and wettability with fountain solution and / or Verdruckmittel and allows easy recovery from operational wear.

According to the invention, there is provided a roller or a blanket as a colorant and / or pressure medium transfer device which comprises a continuous surface covering covering the cover of elastomeric material which contains or consists entirely of a fluoroelastomer and wherein preferably the surface coating has a layer thickness of less / equal to 100 microns and / or has a roughness Ra of less than or equal to 1 micron. The fluoroelastomer can be one or more elastomers selected from the group of elastomeric fluororubber, polyfluoroalkoxyphosphazene or polyfluorosilicone. In particular, in the following, a fluoroelastomer will always be understood explicitly as meaning in each case also an elastomeric fluoro rubber, which represents a particularly preferred embodiment of a fluoroelastomer.

In contrast to teflon-coated rolls, for example, the fluoroelastomer according to the invention provides a surface coating which, like the cover bearing the coating itself, consists of an elastomeric material. As a result, a special adaptation of the roll coating is given to the reference of elastomeric material, including, for example, Teflon coatings such as PTFE, Teflon FEP ® (Tetrafluoroethylene-Hexafluoroproylen-Coplymerisat) or other coatings of non-elastomeric or plastically deformable polymers such as polyvinylidene fluoride and the like would be completely unsuitable, so that a high dynamic load capacity of the roll surface is given, which is both for the Verpressmittelverarbeitung in the nip of two counteracting rolls (Nipp) as well as in the case of blankets is essential. Due to the comparatively thin surface coating, the elastic and / or dynamic properties of the cover are virtually unaffected.

Furthermore, it has been found that the inventive use of such coatings of fluoroelastomer, in particular by a fluorinated rubber, a very defined and consistently consistent transport of the Verdruckmittels or fountain solution can be achieved, so that overemulsions of the Verdruckmittels with fountain solutions, which leads to loss of print quality , can be reliably avoided even in a wide variety of process conditions. In this way, the print quality can be improved and, in particular, even disturbing influences due to changing external conditions or process parameters on the print result can be avoided. The printing process can thus be carried out with an increased process stability, even for example in the case of fluctuating external conditions such as temperature fluctuations, and results over long periods in an always optimal printing result with exact transitions between imaged and non-imaged areas. This is further promoted by the fact that rolls or blankets according to the invention have virtually no tendency to superficially deposit hydrophilizing substances from cleaners, pigments or calcium complexes of paper pulp or paint or the like. These advantages are in particular also compared to rollers in which only fluorinated polyolefins would be incorporated into the elastomer cover and the base elastomer of the cover would form part of the roll surface. such Rollers would not solve the problems underlying the invention.

Furthermore, rolls according to the invention have an excellent back-gap behavior, which clearly exceeds that of rolls in which, for example, fluorinated polyolefins are incorporated into an elastomeric cover and thus high portions of the roll surface are provided by the base elastomer. Here, it is achieved by the surface coating according to the invention that a dampening roller practically no Verpressmittel such. Color splits back into the dampening unit and on the other hand, a coated ink roller virtually no water splits back into the inking unit, which in each case overemulsions are avoided. Further, in ink rollers, the "standing" color memory is reduced in an inking unit and thus the color is converted faster. A blanket of the present invention also does not separate water from the image-forming printing plate, resulting in lower water settings in the wet offset process and avoiding over-emulsions, and on the other hand does not split any color from the previous printing unit from the freshly printed substrate, allowing for much more accurate color tone guidance. Surprisingly, the surface coating according to the invention, depending on the application, meets the requirements mentioned equally.

Furthermore, the blanket according to the invention shows a significant reduction of the paper web deformation in the curling test (for example described as curl and curl test in DIN 6723 and DIN 6724). Thus, conventional blankets usually show a curvature (also called "curl height") of 35 mm, in the best case of 15 mm, whereas blankets according to the invention may have a curvature of ≤ 10 mm, readily ≤ 8 or ≤ 5 mm (each at 50 sheets, solid density about 1.50 DV cyan). As a result, a much more accurate shade guide is possible and Abrißdoublierungen be avoided.

Furthermore, the blanket according to the invention achieves a substantially better print quality with respect to the coloring and color tone guidance of the printed product compared with conventional blankets in multicolor printing. This is achieved on a particularly high accuracy point Verdruckmittelübertragung which leads to a high color accuracy of the printed product. This is particularly important in multi-color printing of crucial importance, since the accuracy of the dot-like transfer of individual color dots of different colors for the printing result is of paramount importance. This is attributed to the particular interaction of the print carrier with the blanket, which also surprisingly results in a particularly smooth running of the printing medium carrier, which also allows higher printing speeds. Without being bound by theory, it is believed that this is due to the particular physicochemical properties of the blanket coating and its surface such as the extra low roughness and elastic properties of the cover layer, also due to the small thickness, the coating has virtually no influence on the Deformation behavior of the cover has what is essential.

Furthermore, the coating of a fluoroelastomer, in particular fluororubber, provides a roller which has a particularly long service life and virtually no changes in its properties over its lifetime, such as surface properties, wetting and swelling behavior with respect to pressure medium and / or dampening solution, transfer of the print - And / or dampening solution to subsequent facilities of the printing press such as a downstream roller or a blanket, cleaning properties, etc. has. This is presumably attributed to the fact that fluoroelastomers, in particular fluoro rubbers, act as a diffusion barrier under the process conditions with respect to a large number of substances such as, for example, solvents of the printing agents, plasticizers of the elastomeric coverings or the like. At the same time it becomes an indiffusion of solvent constituents of the Verpressmittels in the roller as well as out-diffusion of plasticizers from the roller effectively prevented over long periods, so that a highly constant process control is possible. It is understood that the fluoroelastomer coating is preferably plasticizer-free.

Furthermore, rollers and blankets according to the invention are particularly easy to clean, especially of true colors and metallic pigment-containing colors, as used in offset printing, whereby downtime is significantly reduced. In particular, there is also a very significant saving on mineral oil-based cleaners and the use of water-based cleaners is made possible in the first place.

The surface coating is preferably homogeneous in its depth profile, i. has no gradients in terms of its physical properties such as hardness, degree of crosslinking and / or their composition. The same can also apply to the elastomeric cover.

The fluoroelastomer preferably completely covers the elastomeric cover at least in the working area of the roll or blanket, preferably over the entire surface of the roll or blanket. The outer surface of the fluoroelastomer coating is preferably unstructured and as smooth and flat as possible, for example with an average roughness Ra according to EN ISO 4287 or according to DIN 4768 of approximately ≦ 1 μm, ≦ 0.4-0.5 μm, ≦ 0.25 μm or ≤ 0.1 μm.

Preferably, the Fluoroelastomerbeschichtung, preferably at the same time also the elastomeric cover, practically or completely free of pores. The fluoroelastomer coating preferably represents the outermost surface of the roller or of the rubber blanket which comes into contact with the embossing agent, but if appropriate it can also be a further coating layer in the manner of a cover layer be provided. Optionally, intermediate layers may be provided between the fluoroelastomer coating and the elastomeric cover, but preferably no further intermediate layer is provided except for an adhesive or primer layer.

If the roller coating containing the fluoroelastomer contains further particulate constituents, such as fillers and / or non-elastomeric polymers, the fluoroelastomer is preferably provided by the fluoroelastomer as a coherent matrix which absorbs the other constituents so that a continuous spatial network structure is formed from the fluoroelastomer and the coating as a whole is transferred their radial and two lateral or circumferential directions of extension has elastomeric properties. Preferably, the coating is free of particulate, including fibrous, fillers.

It is understood that the elastomeric cover is applied to a stable roll core, which consists for example of a metal or another dimensionally stable material. Preferably, the elastomeric cover, optionally up to an adhesive or primer layer, mounted directly on the roll core, but where appropriate, may also be provided intermediate layers. In the case of a blanket this is usually only one side coated with an elastomeric cover, with several layers of fabric can be provided.

The fluoroelastomer, in particular the elastomeric fluororubber, is preferably present in the surface coating with a content of ≥ 40-50% by weight, preferably ≥ 75 or ≥ 85 or ≥ 90 or 95% by weight, based on 100 parts by weight of the coating in front. The surface coating may consist entirely of the fluoroelastomer, in particular the elastomeric fluororubber. The proportions of fluoroelastomer or fluororubber mentioned may alternatively refer to 100 parts by weight of elastomer or polymer of the coating.

The fluoropolymer or the fluorocarbon rubber is particularly preferably formed from a fluoro rubber latex. Such latexes are particularly advantageous because of their surface properties, which relates in particular to the prevention of overemulsions and the properties as a diffusion barrier for solvents, plasticizers or the like. For the purposes of the invention, latex is understood as meaning a colloidal dispersion of a polymer in an aqueous medium. The latex or polymer can be made naturally or synthetically. The latex may be prepared by emulsion polymerization of suitable monomers or by dispersing polymers in a dispersing agent. The dispersed particles may have an average diameter of from about 0.2 to about 1 or to about 2 or 5 to 10 nm, e.g. about 0.5 nm, without being limited thereto. The latex may contain additives such as dispersants, etc.

Furthermore, it has been found that fluoroelastomers, in particular fluorocarbon rubbers and especially those based on fluorolatices, have a particularly low storage behavior with regard to the uptake and storage of the printing agent or of components of these and / or of fountain solution components such as alcohols or the like.

The fluoroelastomer, in particular the fluororubber, preferably has a high fluorine content, although other halogens, in particular chlorine, may also be present. The atomic ratio of halogen to hydrogen (in particular fluorine to hydrogen) may be ≥ 3: 1, in particular ≥ 4.5 or 5: 1, preferably ≥ 6 or ≥ 7: 1, for example ≥ 8: 1 or 9: 1, optionally also ≥ 15: 1. Preferably, the fluoroelastomer (fluoro rubber) is not perhalogenated / perfluorinated, so that a significant hydrogen content is present, ie the polymer is not perfluorinated / perhalogenated, whereby the hydrophobicity and oleophilicity of the roll surface can be set particularly favorable. For example, can the atomic ratio of hydrogen: halogen (especially in each case hydrogen: fluorine) ≥ 1: 40 or ≥ 1: 19 or ≥ 1: 15 or ≥ 1: 9.5. Preferably, the atomic fluorine content in the total halogen content of the fluoroelastomer or fluororubber or the surface coating containing it is ≥ 75:25, preferably ≥ 90:10 or 95: 5. Most preferably, the entire halogen of the fluoroelastomer (rubber) or surface coating is fluorine.

The fluorine content of the elastomeric fluoropolymer or flurolatex may further be from about 64% to about 74 or about 75% or more by weight, preferably greater than or equal to about 66% to 67% by weight and / or less be equal to 76 wt .-%, for example, about 66 to about 72 wt .-%, more preferably about 66 to about 70 wt .-%, in particular about 68 wt .-% amount (data in each case based on the coating). If appropriate, the fluorine content mentioned here may also refer in each case to the polymeric constituents of the surface coating or to the surface coating as a whole.

The fluoroelastomer or fluororubber may contain or constitute an elastic terpolymer.

Particularly preferably, the fluororubber contains a fluoroterpolymer, which thus has three different monomers, or consists of this. More preferably, the terpolymer is a vinylidene fluoride terpolymer, especially tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer (TFE-HFP-VDF). Optionally, the coating may contain other fluorocoplymers (from 2 different monomers) or terpolymers. Preferably, the weight fraction of terpolymers in the coating is greater than the content of copolymers, preferably TFE-HFP-VDF is present in higher proportions by weight than other copolymers or terpolymers or polymeric constituents, in each case individually or in total. Fluorinated olefin monomers and vinyl fluoride and / or vinylidene fluoride monomers in the coating or in the terpolymer be contained in a proportion of 5 to 90 wt .-% in total to 100 parts by weight of elastomer or terpolymer.

The fluoroelastomer surface coating preferably contains the fluoropolymer, in particular TFE-HFP-VDF, in a content of 5 to 100% by weight, for example 10 to 98% by weight, for example ≦ 80 or ≦ 75 or ≦ 50% by weight. each based on 100 parts by weight of the coating. Preferably, the fluoroelastomer, in particular TFE-HFP-VDF, in each case in a proportion of ≥ 10 wt .-% or ≥ 20 or ≥ 30 or ≥ 50 or ≥ 70 or ≥ 80 wt .-% contained. The proportions by weight may alternatively each refer to 100 parts by weight of polymer of the coating composition.

The fluororubber preferably contains vinyl fluoride and / or vinylidene fluoride monomer units. The proportion of vinyl fluoride and / or vinylidene fluoride monomers based on the total weight of polymer or alternatively based on the total weight of fluoroelastomer in the coating may be 5 to 90 wt .-%, optionally ≤ 75 wt .-%, or ≤ 50 or 30 wt .-%. In particular, the content of vinyl fluoride and / or vinylidene fluoride in the fluororubber may be in the range of 5 to 40% by weight or 10 to 40% by weight or 10 to 30% by weight. The contents mentioned may each refer to the content of vinyl fluoride on the one hand or vinylidene fluoride on the other hand. Optionally, the contents of vinylidene fluoride and / or vinyl fluoride or in each case of vinyl fluoride or vinylidene fluoride may relate to the weight fraction in the surface coating as a whole.

Alternatively, or in addition to the content of vinyl fluoride and / or vinylidene fluoride in the fluororubber, at least one, two or more monomers of another -C = C unsaturated monomer unit may be included, each containing fluorine, optionally adjacent to another halogen especially chlorine, in particular in each case perfluorinated. Such unsaturated monomers may be, for example, one or more monomers selected from the group tetrafluoroethylene, trifluoroethylene, trifluorochloroethylene, pentafluoropropylene, pentafluorochloropropylene, hexafluoropropylene, vinyl fluoride. Optionally, in addition or as an alternative, one or more of the monomers can be selected from the group fluoropropyl vinyl ether, fluoroethyl vinyl ether or fluoromethyl vinyl ether, in particular in each case as perfluoro compound, it also being possible for one or more fluorine atoms to be replaced by another halogen, in particular chlorine. Optionally, the coating may contain a hexafluoropropylene-vinylidene fluoride copolymer or a tetrafluoroethylene-vinylidene fluoride copolymer. One or more of the monomers of the two abovementioned groups may each contain, individually or in total, in a proportion of 5 to 80% by weight, optionally ≦ 75 or ≦ 50 or ≦ 30% by weight, based in each case on 100 parts by weight of polymer of the coating composition be, for example in a range of 5 to 20 wt .-% or between 10 and 20 wt .-%. Optionally, the above proportions may also refer to 100 parts by weight of fluoroelastomer. Optionally, the abovementioned proportions can also refer to 100 parts by weight of the surface coating, which may also contain other components such as fillers or the like.

The elastomeric fluoropolymer may be a block polymer or optionally a random polymer.
The skeleton of the elastomeric fluororubber and / or other polymeric constituents of the coating, preferably all the polymers of the surface coating according to the invention or the coating as a whole, may each be free of heteroatoms, in particular free of ether, ester, amine, silane, acrylate and be or methacrylate groups, in particular also be practically or substantially free of O, N and / or Si atoms. In particular, the skeleton of the polymers can each a practically pure carbon skeleton. The fluororubber and other polymeric components, and optionally also excipients such as dispersants and adhesion promoters, etc., may be substantially or completely free of functional groups, especially side groups, containing O, N and / or Si atoms, such as ether groups, or free of Heteroatoms except halogen. This refers in each case preferably to the uncrosslinked rubber without consideration of corresponding crosslinkers or other auxiliaries. However, the fluorocarbon preferably contains halogenated, in particular perhalogenated, alkyl side groups, it being possible for each halogen to be fluorine, in particular -CF ₃ and -C ₂ F ₅ groups.

Preferably, less than 10 or 5%, preferably less than 1% or 2%, of the atoms of the fluoroelastomer (s) are each present in unsaturated groups relative to 100 carbon atoms of the elastomer, most preferably the fluoroelastomer (fluoro-rubber) has virtually no unsaturated groups ,

The elastomeric fluoroelastomer (fluoro rubber) coating may optionally also comprise non-fluorinated elastomers, for example in a proportion of ≦ 20% by weight, preferably ≦ 10% by weight, more preferably ≦ 5% by weight, based in each case on 100 Parts by weight of polymer. Such elastomers may be non-fluorinated rubber or other materials, such as are useful as a base material for the elastomeric cover. Preferably, however, all elastomer is present as the fluoroelastomer including co- or terpolymer thereof.

Furthermore, it may be preferred if the elastomeric fluoro coating contains at least one or more additional non-elastomeric polymers, in particular non-elastomeric fluoropolymers, which may each contain other halogen atoms, in particular chlorine, preferably as halogen, but exclusively fluorine. The non-elastomeric polymer can be partially fluorinated or perfluorinated. The non-elastomeric polymer may be, for example, a perfluorinated polyolefin, especially polytetrafluoroethylene (PTFE). The non-elastomeric polymers may be present in the coating composition at a level of ≦ 50 or 75 weight percent, ≦ 20 weight percent, optionally ≦ 10 or ≦ 5 weight percent, based on 100 weight parts polymer of the fluoroelastomer coating The coating composition may also be substantially free of such non-halogenated or non-fluorinated polymers.

The non-elastic and / or non-fluorinated polymers may be dispersed, in particular finely dispersed, distributed in the elastomeric coating, for example with a size of the regions of these polymers having an average diameter of less than or equal to about 0.2 nm, up to about 1 or up to about 2 or 5-10 nm, eg about 0.5 nm, without being limited thereto. These areas may be blended into, or virtually fused with, the surrounding polymer.

The non-elastomeric, in particular halogenated or fluorinated, polymer may be present in a proportion of 5 to 80 wt .-% or optionally more, in particular in a proportion of ≤ 60 wt .-%, ≤ 40 or ≤ 20 or ≤ 10 wt. -% be contained in the elastomeric fluoro coating, each based on 100 parts by weight of polymer. However, if desired, the coating composition may also be free of such non-elastomeric polymers or fluoropolymers.

The elastomeric cover of the roll or blanket may in particular consist of one or more elastomers selected from the group consisting of natural rubber (NR), ethylene rubber, ethylene-propylene rubber (EPDM, EPM), styrene-butadiene rubber (SBR), acrylonitrile rubber. Butadiene rubber (NBR, HNBR, XNBR), butyl rubber, polychloroprene rubber, polyurethane rubber (PUR), polyacrylate rubber (ACM), epichlorohydrin rubber, silicone rubber, but not limited thereto be. In the case of blankets, the elastomeric cover is usually made of NBR, FKM or acrylate rubber. It is understood that in general the base elastomer of the cover may be different from that of the fluoroelastomeric coating.

The cover made of elastomeric material can have a hardness of about 15 to about 100 Shore A, for example about 15 or 20 Shore A to about 60 or 85 Shore A, in particular in the range of both a roll according to the invention and a rubber blanket about 20 to about 40 Shore A have. In the case of a blanket, the hardness of the cover carrying the coating is preferably about 50-60 Shore A to about 80-90 SHore A

The hardness of the elastomeric surface coating may vary, i. greater or smaller than the hardness of the supporting elastomeric cover. The degree of crosslinking of the elastomeric surface coating may be different, i. greater or smaller than the degree of crosslinking of the coating carrying the elastomeric cover.

The radial thickness of the cover of elastomeric material may be in the range of about 0.5 to about 50 mm or more, preferably greater than about 1 mm or greater than about 5 mm, for example in the range of 5 to 15 or to 20 mm, which may apply in particular for rollers. In the case of a blanket, the thickness thereof, i. the thickness of the elastomeric cover including the fabric insert, in particular in the range of about 1 to about 10mm, in particular in the range of about 1 or 1.5 to about 5mm, for example in the range of about 1.5 to about 2.2mm.

The surface coating may contain further customary auxiliaries, such as in particular fillers, pigments, anti-aging agents, as well as various other additives such as crosslinkers, acid scavengers, wetting agents, plasticizers or the like. Preferably, however, the surface coating is softeners.

The fillers can be present in a content of ≦ 20% by weight, preferably ≦ 10% by weight or ≦ 5% by weight, based on 100 parts by weight of the coating with the elastomeric fluoropolymer, preferably the filler content is ≦ 2 wt .-%. If fillers are used, these may be, for example, silica, titania, sulfates such as barium or calcium sulfate, carbonates such as barium or calcium carbonate, silicates, silica gels, alumina, aluminosilicates, fibrous materials such as glass fibers, carbon fibers or the like, optionally also carbon black. In particular, the fluoroelastomer or fluororubber coating can be virtually free of filler. Regardless, the coating may be substantially or completely fiber-free.

Furthermore, the coating of the fluoroelastomer can be virtually free of particulate inclusions in the elastomer.

In particular, amine-crosslinkable types can be used as the fluororubber, in particular fluorinated rubber latexes, but also peroxidically or bisphenolically crosslinkable types. Suitable crosslinking agents are widely known, for example aliphatic polyamines such as triethylenetetramine, ethylenediamine, hexamethylenediamine carbamate, ethanolamine, etc., aromatic polyamines such as e.g. Phenylenediamine, or polyamideamines, polyols, including phenol derivatives such as bisphenol, hydroquinones or the like, dicumyl peroxide, dibenzol peroxide; each including their salts. Various other crosslinking systems for fluoro rubber latexes are known which can be used if appropriate.

For example, from 0.5 to 5, for example from about 1 to 2, parts by weight of crosslinker per 100 parts of polymer to be crosslinked may be used per 100 parts by weight of fluoropolymer, without being limited thereto.

It is understood that an adhesive primer layer may be disposed between the elastomeric fluororubber surface coating and the elastomeric cover, using suitable primers such as silane-containing primers.

The radial thickness of the elastomeric fluoro-coating may be in the range of e.g. 1 μ to 1 mm, without being limited thereto, for example in the range of 10 μ to 1 mm. Preferably, the thickness of the surface coating is in the range of 1, 5 or 10 μ to 100 μ. For example, the layer thickness is ≤ 10 μ or ≤ 20-30 μ or ≤ 40-50 μ.

The fluoroelastomer layer, in particular the fluorocarbon rubber layer, can have a wetting angle of ≥ 80 °, preferably ≥ 90 ° or ≥ 100 °, compared to pure water (standard conditions NTP). The fluoroelastomer layer, in particular the fluorocarbon rubber layer, can have a wetting angle of ≥ 60 °, preferably ≥ 70 ° or ≥ 80 ° relative to diiodomethane (standard conditions NTP). The wetting angles were in each case carried out using devices from Krüss GmbH Hamburg using the sessile drop method.

The elongation at break of the fluoroelastomer (fluoro rubber) coating can be> 100%, preferably> 120% or> 150%, possibly also> 170% (in each case determined according to DIN 53504). Preferably, the coating has a reversible extensibility of> 40-50%, preferably> 70%, so that the roller or blanket is exposed to high dynamic loads.

The roller / blanket used in the invention may have an elastomeric cover which has a substantially continuous hardness gradient over at least part of the reference layer thickness, in particular continuous hardening drop towards the center axis / midplane of the roll / blanket. A roller with such a cover is the DE 101 29 107, the disclosure of which is hereby incorporated by reference in their entirety. It is understood that the same can apply to the cover of a blanket. The hardness gradient preferably extends over a difference of the effective hardness of the roll coating of more than 5 Shore A, preferably more than 10 or 20 Shore A. The term "effective hardness" is defined in the sense of DE 101 29 107. Preferably, the region of the layer having the hardness gradient is arranged on the roll surface / blanket surface or in an area starting from this to a depth of approximately 10 or approximately 20 μm of the cover. The layer thickness of the hardness gradient may be greater than or equal to 0.05 or greater / equal to 0.1 mm and less than or equal to about 1 to about 2 mm, but also have a greater layer thickness. The hardness gradient may be generated by a gradient of one or more of the components of the roller coating, in particular one or more components from the group fillers, hardeners, crosslinking agents, activator, photoinitiator, monomers and oligomers of a polymeric material and plasticizer. Particularly preferably, the hardness gradient is produced by a gradient of the degree of crosslinking of a component of the reference material, in particular of a matrix material thereof. The crosslinking agent may be selected from the group consisting of peroxide, sulfur, halide, sulfur halide or the like. In particular, the hardness gradient can be introduced into the cover material by diffusion or migration of a hardness-changing substance or a precursor thereof from the surface of the roll cover / blanket cover. It is understood that the hardness gradient refers to the cover material of the roll / blanket without regard to the applied fluoroelastomer coating. The combination of the fluoroelastomer surface coating, which co-determines superficial forces, and the described hardness gradients on the surface or near the surface region of the cover, which co-determines the dynamically acting forces, results in particularly advantageous roller / blanket properties with regard to the preparation of the dampening / Verpressmittels in Nipp (nip) or in the gap between the blanket and plate cylinder or print carrier on the other hand, which has particularly advantageous effects on the transport and processing of the wet / colorant.

Surprisingly, the roller according to the invention has also proven itself as a laminating roller of a laminating system, since the roller assumes no plastic or no polyethylene in a plastic lamination, in particular a lamination of polyolefins such as polyethylene, thus leading to improved products.

The elastomeric surface layer of a roll or blanket according to the invention may each be subjected to a non-mechanical surface treatment in order to improve the surface properties, e.g. to vary the wetting properties with respect to the printing and / or dampening agent or the above-mentioned wetting angle with respect to water and / or diiodomethane. In particular, the surface treatment may be a physical treatment for altering the electrostatic properties of the surface. The surface treatment may e.g. in the form of a plasma treatment, corona discharge and / or electrostatic discharge. The plasma may in particular be an oxidizing or an atmospheric plasma.

To produce the roll according to the invention, it is possible to use a roll with an elastomeric cover in which the elastomeric covering is optionally applied by an adhesive layer on a rigid roll core, for example made of metal. The elastomeric cover may be cleaned by a solvent with a primer, e.g. B. a silane primer, wherein the primer in a suitable solvent by suitable methods such as spraying, brushing, doctoring o. The like. Is applied. After exposure to the primer for a sufficiently long period, eg. B. 30 minutes, if necessary slightly elevated temperature (eg, 40 ° to 50 °), the fluoroelastomer (eg, fluoro rubber) may be applied as a water-based fluororubber latex. The application can be done by spraying, brushing, dipping, knife coating or the like. The fluoro-rubber layer can be produced by a single layer application, if necessary, to achieve greater layer thicknesses, a multiple application may be necessary. The fluoro rubber latex may be applied after mixing with the curing agent or crosslinking agent together with this. Optionally, the latex may also be previously diluted. Generally, after application of the fluoroelastomer, the layer may be dried for a sufficiently long period of time, for example, for one to two hours, with drying not always required. The drying can be carried out at room temperature or at somewhat elevated temperature. Subsequently, curing of the fluoroelastomer coating may be carried out under suitable conditions, in particular at an elevated temperature, such as for a period of 1 to 10 hours at temperatures in the range of 80 ° to 150 °, for example 100 ° to 120 °, the conditions of may depend on the elastomer or rubber used. The drying and / or curing is thus generally at your temperature, which is higher than the film-forming temperature of the latex. In general, the roll can be used without mechanical post-treatment of the surface coating such as grinding, polishing, etc. suitable for use.

The same applies to the production of a rubber blanket coated according to the invention, wherein a rubber blanket with an elastomeric coating, which may have a carrier layer in the form of a woven, mesh, nonwoven or the like, is coated under suitable conditions.

Rolls according to the invention can be used in printing machines or printing units of printing presses, each of which has a different color on the respective print carrier, for example a paper web apply, be used as dampening solution transfer roller and / or as Verdruckmittelübertragungswalze. The rolls according to the invention can each be arranged in the dampening unit and / or the inking unit of the printing press, which supplies fountain solution or printing agent substantially separately from the printing cylinder to the imaged print carrier, the rollers can also be part of a combined dampening / inking unit, which dampening solution and Verdruckmittel feed the printing cylinder as an emulsion. The rolls according to the invention can each be designed as scoop roll, metering roll and / or ductor roll, preferably they are arranged downstream of the scoop roll. This applies to both dampening and inking. One, several or all of the rollers of the dampening and / or inking unit can be designed according to the invention. In an inking unit, the rollers according to the invention can operate in particular against a distributor roller which has a non-elastomeric coating or a metallic or ceramic surface which may optionally be coated to modify the surface properties, the hardness of the distributor roller being substantially higher than that of the elastomeric roller Reference is and the distributor roller performs an oscillating movement in the longitudinal direction. In particular, the rolls according to the invention can be wet dip rolls and wet metering rolls in film dampening units.

Furthermore, the roller according to the invention may be a laminating roller of a plastic laminating system, in which a substrate is laminated with a plastic, in particular a polyolefin, such as polyethylene.

Furthermore, the dampening solution and / or ink transfer devices according to the invention may be in the form of a blanket, which is usually clamped in the printing press on a cylinder and from there applies the Verdruckmittel on the print carrier in order to print this. The blanket is usually provided at the edges with rails or attached flat on a plate, for example glued to be mounted on the blanket cylinder can.
The dampening solution and / or colorant transfer devices according to the invention may in particular be those of offset printing machines, which are provided as a roller and / or blanket in the respective printing unit of the printing press, which in each case prints a given printing means. The printing machine may include a blanket washing device as usual.

Preferably, the roller which directly follows the roller according to the invention in the printing machine in the dampening solution / transfer printing medium transport direction and works against it to form a nip has a higher surface tension than the first roller.

Conventionally, conventional rollers must be laboriously refurbished after wear-induced abrasion by replacing the elastomeric roller cover as a whole, with generic rubber blankets a restoration of which is practically impossible.

In contrast, rollers according to the invention can be restored particularly easily after wear-related abrasion. The roller to be restored usually still has a surface coating containing or consisting of fluoroelastomer (fluororubber) in a significant thickness, for example 5 or ≥ 10 μm. In this roll to be restored, the surface may first be abraded slightly to produce a smooth and even surface, preferably with the fluoroelastomer coating completely and even a small amount of underlying elastomeric cover removed, eg, a thickness of about 10 microns; Fluorelastomer coating also only partially removed. Subsequently, the fluoroelastomer or the fluororubber can be applied as latex by suitable coating method again to the desired thickness, for example by dipping, spraying, brushing, knife-coating or the like. After drying and curing of the fluoroelastomer under suitable conditions, which may correspond to those of the new production of the roller, a functional roller can be produced again without completely removing the elastomeric cover. In most cases, it is also possible to dispense with further surface treatment, in particular regrinding or polishing, even if this can be carried out if necessary. The restoration of the roller is thereby considerably simplified, apart from the fact that the rollers anyway have a particularly long life of about 1 to 2 years due to the fluoroelastomer coating, compared with a life of about half a year in conventional rollers.

Figur 1

eine Querschnittsdarstellung einer erfindungsgemäßen Walze,

Figur 2

eine Querschnittsdarstellung eines erfindungsgemäßen Gummituchs,

Figur 3

eine schematische Ansicht einer Druckmaschine mit erfindungsgemäßer Walze und Gummituch.

The invention will be described below by way of example and explained by way of example with reference to FIGS. Show it:

FIG. 1

a cross-sectional view of a roller according to the invention,

FIG. 2

a cross-sectional view of a blanket according to the invention,

FIG. 3

a schematic view of a printing machine with inventive roller and blanket.

Figure 1 shows a roll according to the invention, as it can be used as dampening solution transfer roller, in particular dampening roller, or Verdruckmittelübertragungswalze, in particular Verdruckmittelauftragswalze in an offset printing press. The roller 1 has a core 2 of a dimensionally stable material such as a hard plastic or metal, for example steel or aluminum. On the core 2, a roll cover 3 is applied from an elastomeric material, wherein between the core and cover an adhesive layer (not shown) is provided. The roll cover may be made of a suitable elastomeric material, for example acrylonitrile butadiene rubber (NBR), butyl rubber or the like. The reference has a radial Thickness of about 10 mm and a hardness of about 30 Shore A on.

A coating of an elastomeric fluororubber in the form of a latex, which comprises TFE-HFP-VDF terpolymer in combination with PTFE in a weight ratio of about 60:40, is applied to the roll cover 3 by means of a primer layer (not shown). The fluorocarbon coating is filler-free and free from plasticizers and has a thickness of about 25 μm. The outer surface of the coating 4 of elastomeric fluororubber directly forms the outermost surface of the roller, which comes into contact with the dampening or Verdruckmittel. The surface of the elastomeric fluoro-coating is treated by an atmospheric plasma.

FIG. 2 shows a rubber blanket 5 according to the invention, which has a middle fabric layer 6, which is coated in a suitable thickness, for example about 2 mm, with a cover 7 made of elastomeric material such as NBR, FKM or acrylic rubber. The cover has a hardness of about 60 Shore A. The elastomeric cover 7 is on one side, possibly also on both sides, provided with a surface layer 8 of elastomeric fluoro rubber, which may have a thickness of about 30 μ and from a TFE-HFP-VDF copolymer in combination with PTFE in a ratio of approx 70:30 parts by weight. Again, the elastomeric fluoro rubber layer filler and plasticizer-free. Again, preferably between the fabric layer 6 and the elastomeric cover 7 on the one hand and the outer surface of the elastomeric cover 7 and the surface layer 8 is provided in each case a bonding agent layer (not shown). With regard to the compositions and properties of the elastomeric cover as well as the surface layer, reference is otherwise made to the exemplary embodiment according to FIG. For attachment to a cylinder, the opposite lateral edges can be provided with suitable fastening rails or the blanket can be glued to a plate.

In both embodiments, the fluorine content of the elastomeric fluorocarbon coatings is about 68% by weight or even up to about 75% by weight, based on the coating, the wetting angle with respect to water is about 95 °, and the wetting angle with respect to diiodomethane is about 80 ° °.

In a wear-related abrasion roller or the blanket according to the invention can be particularly easily restored by the surface is cleaned in a roller or blanket with a remaining coating of elastomeric fluororubber, which has, for example, a thickness of 5 to 10 microns, and then new fluorinated rubber is applied, which preferably corresponds in composition to that of the already existing layer, without this always being absolutely necessary. The provided with a hardener or crosslinker fluorocarbon coating, the z. B. is applied by a spray process can then be dried for a sufficient period of time such as one to two hours and then cured at elevated temperature, for example, for three to four hours at 100 ° to 120 ° C. For thicker desired Fluoroelastomerschichten a repeated application with subsequent curing is necessary. The roller can then be used without further surface treatment.

Roll and blanket according to Figures 1 and 2 have a hardness gradient, wherein at the surface of the elastomeric cover 7, ie adjacent to the surface coating 8, followed by a continuous hardness gradient with decreasing towards the inside hardness. The continuous hardness gradient extends over a layer thickness of about 0.5 to about 1 mm, wherein the hardness drops from about 60 Shore A of the near-surface layer of the cover to about 30 Shore A of the inner layer. The hardness gradient has been generated by a gradient of the degree of crosslinking of the elastomeric cover material by diffusing a crosslinking agent into the cover.

The fluoroelastomer coating was then applied.

Figure 3 shows an offset printing machine 10 with a dampening unit 11, in particular a film dampening unit, and a printing unit 12 for printing a print carrier 13 such as a paper web. The dampening unit 11 has a fountain solution reservoir 14, from which by means of a fountain roller 15 (also known as scoop roller) a fountain solution such as auxiliaries added water is conveyed, wherein the conveyed dampening solution is metered by a working with a small gap against the dipping roller metering roller 16. The dampening solution film transferred from the fountain roller to the metering roller is then transferred to at least one dampening roller 17 and then from the dampening unit 11 to the plate cylinder 18 of the printing unit 12 Rollers are then not affected by the strongly disturbing Verpressmittelrücklauf and in the outlet of the respective nip (Nipp) Cording formation (formation of strip-like inhomogeneities of the dampening solution film at average speeds of the rollers) and streaking can be avoided. The entire, through the nip enforced water film is passed due to the roll coating according to the invention the following roller and a back-splitting or returning dampening solution film, as can be found on conventional rolls is reliably avoided under different environmental and process conditions.

It is understood that the dampening agent metering roller 16 can also abut directly on the immersion roller 15 only on the submersible roller 15 and the dampening solution application or transfer roller. Instead of the plate cylinder 8 may also be provided a flat pressure plate.

On the plate cylinder 18 is further by the roller 26 of an inking unit 25, a printing ink or generally a Verdruckmittel applied. The ink is in this case conveyed from a paint reservoir 27 by means of a ink fountain roller 28 and transferred by means of an elastomer-coated lifter roller 29 to a distributor roller 30, wherein the lifter roller 29 between the ink fountain roller 28 and the distributor roller 30 is oscillated back and forth. The distributor roller 30 in this case has a metallic, ceramic or plastic surface. Between the following ink rollers 26 and distributor rollers 30, a homogeneous ink film of desired thickness is produced, which is transferred to the plate cylinder 18. It is understood that the inking unit 25 may alternatively be embodied as a film inking unit in which the ink fountain roller is doctored off and has no direct contact with a non-elastomeric coated film roll running at machine speed.

The plate cylinder 18 has wettable by the dampening hydrophilic and wettable by the printing agent hydrophobic areas, so that a printed image is formed by the arrangement of the hydrophobic areas. The printed image is then transferred from the plate cylinder 18 to a rubber blanket-covered blanket cylinder 20 and from there to the print carrier 13. The print carrier 13 is in this case carried out between the blanket cylinder 20 and a counter-pressure cylinder 21, which bear against the material 13 on both sides. Said arrangement corresponds to that of an offset printing method, but it should be understood that the invention is not limited to this method. It is understood that optionally dyeing and dampening solution can also be performed in combination, so that the plate cylinder 18 as intended a colorant dampening solution emulsion is performed.

One, several or all of the rolls 15, 16, 17, 26, 29 and / or the rubber blanket covering the blanket cylinder 20 may be designed according to the invention, for example according to the embodiments of Figures 1 and 2.

LIST OF REFERENCE NUMBERS

1

roller

2

core

3

elastomeric cover

4

surface coating

5

blanket

6

tissue layer

7

elastomeric cover

8th

surface coating

10

press

11

dampening

12

printing unit

13

print carrier

14

Dampening solution reservoir

15

dipping roller

16

metering

17

Dampening solution applicator roller

18

plate cylinder

20

Blanket cylinder

21

Impression cylinder

25

inking

26

ink roller

27

ink reservoir

28

ink fountain roller

29

vibrator roller

30

distributor roller

Claims (24)

Roller or blanket for a printing press, in particular offset printing press, or roller as laminating roller of a laminating machine, wherein roller or blanket have a cover of an elastomeric material having an outer surface for dampening and / or Verpressmittelübertragung in the printing press, to directly or indirectly To transfer wet and / or Verpressmittel on a print carrier, wherein the dampening and / or Verpressungsmittel transmitting outer surface is provided by an elastomeric surface coating of the cover, characterized in that the surface coating contains a fluoroelastomer, in particular an elastomeric fluorinated rubber, or at least in essentially completely consists of this and the surface coating has a layer thickness of less than or equal to 100 microns and a roughness Ra of less than or equal to 1 micron. Roller or blanket according to claim 1, characterized in that the surface of the surface coating has a roughness Ra of less than or equal to 0.4 μm. Roller or blanket according to claim 1 or 2, characterized in that the fluoroelastomer a fluoro rubber latex is formed. Roller or blanket according to one of claims 1 to 3, characterized in that the fluorine content of the surface coating in the range of about 64 wt .-% to about 75.5 wt .-% based on the polymeric coating constituents or on the surface coating as a whole is. Roller or blanket according to one of claims 1 to 4, characterized in that the surface coating is not perfluorinated and that the atomic ratio fluorine: hydrogen of the surface coating is greater than or equal to 5: 1. Roller or blanket according to one of claims 1 to 5, characterized in that the fluoroelastomer contains vinyl fluoride and / or vinylidene fluoride monomer units. Roller or blanket according to one of claims 1 to 6, characterized in that the fluoroelastomer is or comprises a terpolymer. Roller or blanket according to one of claims 1 to 7, characterized in that the fluoroelastomer contains or consists of a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer. Roller or blanket according to one of claims 1 to 8, characterized in that in the coating, the fluoroelastomer or the terpolymer is contained in a proportion of 5 to 98 wt .-% to 100 parts by weight of the coating. Roller or blanket according to one of claims 1 to 9,
characterized in that the elastomeric fluoropolymer is a block polymer. Roller or blanket according to one of claims 1 to 10, characterized in that the fluoroelastomer-containing surface coating additionally contains a non-elastomeric polymer, including fluoropolymer. A roll or blanket according to claim 11, characterized in that the non-elastomeric polymer, including non-elastomeric fluoropolymer, is present in a proportion of up to 75% by weight to 100 parts by weight of elastomer in the surface coating. Roller or blanket according to one of claims 1 to 12, characterized in that the surface coating has an elongation at break of> 100% and / or a reversible extensibility of> 50%. Roller or blanket according to one of claims 1 to 13, characterized in that the fluoroelastomer-containing surface coating has a thickness of up to 50 microns. Roller or blanket according to one of claims 1 to 14, characterized in that the surface coating has a wetting angle to water of ≥ 80 ° and / or a wetting angle to diiodomethane of ≥ 60 °. Use of a roller according to one of claims 1 to 15 as a dampening solution roller or dampening agent metering roller of a dampening unit or as Verdruckmittelheberwalze or Verdruckmittelübertragungswalze an inking unit of a printing machine, in particular offset printing machine. Use of a roller according to claim 16, characterized in that the roller according to claim 1 to 16 operates against an immediately following in dampening solution / Verdruckmitteltransportrichtung roller having a higher surface tension than the former roller. Use of a roller according to one of claims 1 to 17 as dampening solution applicator roll or as Verdruckmittelauftragswalze in a printing machine, in particular offset printing machine, wherein the roller transfers the dampening solution and / or the Verdruckmittel directly to an imaged printing cylinder, from which this directly on a blanket and then immediately is transferred to the print substrate to be printed. Printing machine, in particular offset printing press, with a roller and / or a rubber blanket according to one of Claims 1 to 15. A process for producing a roll or blanket according to any one of claims 1 to 15, wherein a roll or blanket having an outer elastomeric coating containing or consisting of a fluoroelastomer, in particular fluoro rubber, is provided which at least partially continuously transmits the elastomeric cover in a significant amount Coating layer is covered and its thickness is reduced by wear abrasion, further comprising the steps of applying a Fluoroelastomers by a suitable application method and curing of the Fluoroelastomers, optionally with preliminary predrying and / or optionally with repetition of the order and the curing of Fluoroelastomers until the desired Layer thickness of the surface coating containing the fluoroelastomer. A method according to claim 20, characterized in that before the application of the fluoroelastomer the existing elastomeric surface coating is removed completely or even into the elastomeric reference. Process according to Claim 20 or 21, characterized in that the fluoroelastomer is applied by application of a suitable aqueous dispersion. Method according to one of claims 20 to 22, characterized in that the roller is provided after application of the elastomeric surface layer containing or consisting of a fluoroelastomer to achieve the desired layer thickness for use in a printing press, without a further mechanical surface treatment such as grinding, polishing or another To carry out coating, but optionally containing a cleaning step of the roll surface. Method according to one of claims 20 to 23, characterized in that the elastomeric surface layer is subjected to a surface treatment in the form of a plasma treatment, corona discharge and / or electrostatic discharge.

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