Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/006—Printing plates or foils; Materials therefor made entirely of inorganic materials other than natural stone or metals, e.g. ceramics, carbide materials, ferroelectric materials

Definitions

• the invention relates to a metal plate which is suitable, in particular, for the manufacture of a gravure printing sleeve comprising a mechanically engravable metal layer.
• the metal plate according to the invention is characterised by the fact that at least one mechanically engravable harder top layer is present on the mechanically engravable metal layer.
• said top layer is wear-resistant, the degree of wear resistance being chosen to suit the utilisation situation.
• the adhesion of the top layer to the mechanically engravable metal layer has to be good. Both layers must not separate from one another during the mechanical machining.
• the top layer has a material stretch of 0.1-5%, expediently approximately 2.5%. If the material stretch is higher, the material is too soft, as a result of which a sharp pattern cannot be obtained or is difficult to obtain. If the stretch is lower, the material is too hard or too brittle and, although a good pattern definition can be obtained, this is at the expense of excessive chisel wear. It is assumed that the structure of the engraved layer must be from finely crystalline to amorphous.
• the layer according to the invention has a Vickers hardness of approximately 400-1050, preferably 450-500, at the surface, while the thickness of the top layer is not more than 15 ⁇ m, preferably approximately 2 ⁇ m.
• the presence of such a top layer does not appear to affect the application of a pattern having a high accuracy and reproducibility, and the acceptable service life of the engraving tool.
• the upper limit of the thickness of the top layer is critical insofar as, if said limit is exceeded, the hardness of the material will acquire an adverse effect on the tool and shorten the service life thereof, while the engraving quality will be adversely effected.
• the thickness and other characteristics of the top layer must be such that during the mechanically engraving process at least through the whole thickness of said top layer can be engraved.
• the top layer is thus also subjected to the mechanically engraving and is not a (protective) layer applied afterwards.
• the top layer preferably has a uniform thickness.
• the top layer is composed of an electrolessly deposited layer of a metal or the alloy.
• a metal or the alloy examples include phosphor nickel, boron/nickel, tin/nickel, nickel and nickel/cobalt, the layers being hard or being thermally hardenable, as is known in the case of phosphor nickel.
• the top layer may, however, also be obtained by electrolytic deposition but ion implantation techniques can also be used in principle to produce the desired engravable system of layers.
• the mechanically engravable metallic layer may be composed of a relatively soft material, for example a metal layer having a Vickers hardness of approximately 80 to 350 and a low stretch. Examples thereof are soft nickel, copper, aluminium, iron, various alloys, zinc, etc.
• the engravable metal layer may, however, also be composed at least partly of a polymer which must, obviously, have the properties of hardness and stretch specified above, and in order to be able to apply the harder top layer, it must also be metallisable.
• the invention also relates to a composite for producing a metal structure, suitable for use in printing systems, composed of a support and a metal plate comprising a mechanically engravable metal layer, which is characterised by the fact that the metal plate is a metal plate in accordance with the invention.
• the finished roller can be manufactured simply by clamping the present structure onto a support in the form of a roller.
• the engraving in the relatively soft metal layer already being provided with a thin top layer yields a pattern definition such as that obtained with fine-grained types of metal, such as hard copper.
• a chisel or diamond In relation to the life of the engraving tool, in this case a chisel or diamond, however, no reduction in the service life is observed with the composite of layers according to the invention. The image quality obtained in therefore particularly good.
• a layer of soft nickel, hard copper, aluminium, zinc, iron and various alloys can be chosen for the relatively soft engravable metal layer having a low stretch.
• the hardness of said layer is usually 80 to 350 in Vickers units.
• the support it is not necessary for the support to be provided with a separate metal plate if both are produced from the same metal or the same alloy.
• a solid support for example a solid roller, will obviously also be satisfactory in that case.
• the thickness of the mechanically engravable metal layer must, however, be such that the underlying support roller is not affected by the engraving.
• An engravable metal layer thickness of approximately 50 ⁇ m will therefore usually be sufficient, although deviating thicknesses of, for example, 100 ⁇ m or 25 ⁇ m are also possible without difficulty, obviously depending on the pattern to be transferred or the desired engraving depth.
• engraving is understood as meaning mechanical machining based on cutting machining with the associated mechanical deformation using a forming tool such as a scriber, chisel, diamond etc.
• the invention also relates to a method for the manufacture of an composite metal plate, in particular suitable for use in printing systems, in which at least one mechanically engravable metal layer is applied to a support, said method being characterised by the fact that there is furthermore applied to the mechanically engravable metal layer at least one mechanically engravable top layer having a hardness which is greater than the hardness of the engravable metal layer.
• the adhesion of the top layer to the mechanically engravable metal layer must obviously be good; said layers must not separate from one another during the mechanical machining.
• a wear-resistant top layer is applied.
• the Vickers hardness of the wear-resistant top layer is preferably approximately 450-750, expediently 500-680, but in particular approximately 650.
• the thickness of the top layer is, in particular, not more than 10 ⁇ m, preferably approximately 2 ⁇ m.
• the thickness of the top layer is greater than 15 ⁇ m, depending on the type of top layer, there may be present a structure which has preferred fracture lines as a consequence of dislocations which may be present in the crystal structure, which structure adversely affects the achievement of a good image quality.
• a thickness is too great to be able to apply the finer details during the mechanical machining and the effect of excessive chisel wear still occurs.
• the top layer is applied by electroless deposition of a metal or metal alloy.
• a metal or metal alloy Such a process promotes the achievement of a uniform thickness distribution of the top layer, as a result of which an excellent reproducibility of the image quality is achieved.
• electroless depositions of phosphor nickel, boron/nickel, tin/nickel, titanium nitride, boron nitride and other similar layers may also be used, each type of top layer having its own ideal layer thickness for the maximum effect within the scope of the invention.
• the adherence of the top layer to the engravable metal layer must obviously be good. If both layers separate from one another during the application of a pattern, it will be impossible to achieve a good image definition in accordance with the inventive idea.
• the mechanically engravable metal layer may, for example, be composed of nickel or aluminium. Insofar as they can be metallised in the production of a printing sleeve and thermally and mechanically stable, the use of special plastics is also not excluded. Usually, said layer is applied to a support, but is obviously also possible for a solid metal plate or roller to be used.
• the thickness of the mechanically engravable metal layer is chosen to suit the pattern to be transferred and the desired pattern depth. Usually, this thickness will be approximately 50 ⁇ m; a thickness of the mechanically engravable layer of, for example, 25 ⁇ m or 100 ⁇ m may, however, be more expedient in certain application forms.
• the top layer will preferably be composed of an electroless hardenable nickel or nickel alloy layer or thin chromium layer.
• the Vickers hardness thereof is approximately 450-550, but it can be increased to approximately 1100 by applying a conventional heat treatment. Increase in the hardness can also be brought about on the basis of particle bombardment or treatment with high-energy laser-based and/or magnetron-based radiation.
• the mechanically engravable metal layer advantageously has a Vickers hardness of approximately 80-350. Since an accurately defined pattern has to be applied in the metal plate according to the invention, a metal layer with finely crystalline structure will give a better result than a metal layer with a coarse structure. It has furthermore been found that excellent results are achieved if the specification of the layer exhibits a combination of a relatively low hardness with a low stretch value.
• the requirements to be imposed on the bath are high dispersing power (even layer thickness), a finely crystalline deposition quality, thermal resistance, the correct Vickers hardness with respect to the base layer and low stretch value (NiCo, NiP, NiSn etc.), and possibly hardenability in additional process steps.
• the invention also relates to a roller provided with a pattern achieved by mechanical engraving, which is suitable, in particular, for use in printing systems, comprising a support roller and a metal plate, which is characterised in that the metal plate is a plate in accordance with the invention.
• the invention also relates to a process for mechanically engraving a pattern into an engravable metal basic layer, wherein before said engraving at least one thinner, engravable, harder top layer is applied, and the composite of layers is thereafter engraved to within the metal basic layer to obtain a pattern.
• the top layer is preferably wear-resistant. Expediently said layer has a material stretch of from 0.1-5%, preferably approximately 2.5%.
• the Vickers hardness of the top layer is from about 400-1050, preferably 450-500, whereas its thickness is preferably not more than 10 ⁇ m, expediently approximately 2 ⁇ m, the thickness preferably being uniform.
• the top layer is hardenable after being provided on the metal basic layer.
• the starting point was a standard gravure printing sleeve having a thickness of approximately 300 ⁇ m.
• the Vickers hardness was approximately 450, while the material stretch was 7%.
• the surface of said sleeve was subjected to a heat treatment with laser radiation, as a result of which the surface layer having a thickness of 50-150 ⁇ m acquired a Vickers hardness of 200-350 and a material stretch of ⁇ 3%.
• a layer of phosphor nickel having a thickness of approximately 2 ⁇ m was deposited on the gravure printing sleeve thus obtained by an electroless coating method.
• Said top layer had a Vickers hardness of 450-500.
• the metal composite thus obtained was subjected to a mechanical engraving machining using a chisel.
• Thermal treatment of the composite thus produced yielded a hardening of the top layer to a Vickers hardness of 900-1000.
• the pattern configuration produced did not have the known disadvantages, in the case of which the machining edges of the scribing are ragged and fuzzy, resulting in poor image definition.
• an examination of the chisel used showed that there was no wear image at all which could eventually limit the life thereof.
• a copper layer having a thickness of 500 ⁇ m is applied to a hard-nickel roller (Vickers hardness 450).
• a layer of electroless nickel having a thickness of 2 ⁇ m is applied to said copper layer.
• the Vickers hardness of the electroless nickel layer was 550.
• a desired pattern was then engraved in said roller with the aid of a helioklischograph.
• the engraved roller thus produced to a heat treatment (15 min, approximately 800°C)
• the Vickers hardness of the electroless nickel top layer was increased to 1050.
• the wear resistance of the finished roller is therefore increased appreciably.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Inorganic Chemistry (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Printing Plates And Materials Therefor (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=19859957

Family Applications (1)

Country Status (3)

Cited By (8)

Families Citing this family (1)

Citations (6)

• 1991
  • 1991-11-25 NL NL9101971A patent/NL9101971A/nl not_active Application Discontinuation
• 1992
  • 1992-11-23 EP EP92203621A patent/EP0545468A1/de not_active Withdrawn
  • 1992-11-25 JP JP31524192A patent/JPH05221171A/ja active Pending

Patent Citations (6)

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