EP2438218B1 - Workpiece with two nickel-containing layers - Google Patents

Description

The invention relates to a gravure cylinder with at least one nickel-containing layer.

In gravure printing, predominantly cylinders with an engraving layer of copper and a wear protection layer made of hard chrome are currently used. Here, the galvanic deposition of chromium happens with a poor efficiency.

The DE 102 14 989 A1 shows a printing cylinder with an intended for engraving surface coating. Instead of a pure copper layer with a microhardness of about 200 HV either a surface coating of pure nickel and / or mixed crystal alloys and / or composite layers is proposed which have copper or nickel as Hauptkompönente.

The EP 0 545 468 A1 shows a metal plate for a gravure sleeve, which is clamped on a support and is suitable for mechanical engraving. A engravable metal layer has a thickness of 25 microns, 50 microns or 100 microns, and an outermost layer has a thickness of less than 10 microns. The engravable metal layer usually has a hardness of 80 to 350 HV, and the outermost layer preferably has a hardness of 450 to 750 HV. As a concrete combination of materials, in Example II, for the engravable metal layer, copper is given and for the outer layer chemically deposited nickel. For the engravable metal layer, a group of materials is given, which are soft nickel, hard copper; Aluminum, zinc, iron, alloys and special plastics. For the outermost layer, a group of materials is disclosed comprising metals, in particular chromium, alloys and ceramic material from the subgroup of titanium nitride, boron nitride and chromium carbide. Chemically deposited phosphorus-nickel, boron-nickel, tin-nickel, nickel and nickel-cobalt are also mentioned.

It is an object of the invention to provide a new gravure cylinder.

According to the invention, the object is achieved by a gravure cylinder according to claim 1. In such a gravure cylinder, the recycling of the first and second layer is facilitated because both layers have nickel as the main component. The gravure cylinder is also suitable for laser engraving.

An advantageous development results from the claim 6. In such a gravure cylinder, the recycling of the first and second layer is particularly well possible because it is in spite of the two layers is essentially a single-grade single-metal system.

The object is also achieved by a gravure cylinder according to claim 2. A layer containing nickel and hexagonal boron nitride, has advantageous properties and can also serve as a wear protection layer in particular.

Fig. 1

eine schematische Darstellung eines Tiefdruckzylinders in geschnittener Darstellung,

Fig. 2

einen Querschnitt durch den Tiefdruckzylinder aus Fig. 1,

Fig. 3

eine schematische Darstellung einer Galvanisieranlage,

Fig. 4

einen Querschnitt durch einen Tiefdruckzylinder,

Fig. 5

einen Querschliff durch einen Grundkörper mit einer Schicht, welche Nickel und hexagonales Bornitrid enthält,

Fig. 6

einen Querschliff durch eine Schicht aus Nickel und hexagonalem Bornitrid, und

Fig. 7

den Querschliff aus Fig. 5 im Original.

Further details and advantageous developments of the invention will become apparent from the hereinafter described and illustrated in the drawings, in no way as a limitation of the invention to be understood embodiments, and from the dependent claims. It shows

Fig. 1

a schematic representation of a gravure cylinder in a sectional view,

Fig. 2

a cross section through the gravure cylinder Fig. 1 .

Fig. 3

a schematic representation of a galvanizing plant,

Fig. 4

a cross section through a gravure cylinder,

Fig. 5

a transverse section through a base body with a layer containing nickel and hexagonal boron nitride,

Fig. 6

a transverse section through a layer of nickel and hexagonal boron nitride, and

Fig. 7

the cross section Fig. 5 in the original.

Fig. 1 shows a gravure cylinder (generally: workpiece) 10 having a core (in general: base body) 12, a first layer 14, which is applied to the core, and a second layer 16, which is applied to the first layer 14. The longitudinal axis 18 of the gravure cylinder 10 is indicated schematically. As the core 12, for example, a cylinder made of steel, copper or zinc is used.

The first layer 14 is preferably made of pure nickel, and the second layer 16 is preferably made of a composition NiX, where X is e.g. Silicon carbide (SiC), phosphorus (P), hexagonal boron nitride (h-BN) and / or another, preferably non-metallic component (additive), which together with the nickel has better anti-wear properties than pure nickel. The mass fraction of the non-metallic constituent in the second layer 16, ie the relative mass of the non-metallic constituent to the total mass of the substance mixture, is preferably between 0.001 and 0.15, more preferably between 0.003 and 0.12, more preferably between 0.01 and 0.10, more preferably between 0.03 and 0.09.

The wear, ie the continuous loss of material from the surface of a solid body, caused by mechanical causes, depends on a variety of material properties. In general, a high hardness, anti-adhesive properties and a low coefficient of friction are advantageous.

Pure, electrodeposited nickel has a hardness in the range of 350 to 550 HV 0.05, depending on the galvanic bath used, and the second Layer preferably has a hardness of at least 450 HV 0.05, for example between 450 and 750 HV 0.05. The specification 350 HV 0.05 indicates, for example, that the hardness test according to Vickers with a test force of 0.05 kp a hardness value of 350 was measured. 0.05 kp (kilopond) roughly corresponds to the weight of a mass of 50 g, and 1 kp = 9.80665 N.

The first layer 14 preferably has a layer thickness of 20 to 210 μm, more preferably 30 to 200 μm, more preferably 30 to 80 μm, and the second layer 16 preferably has a layer thickness of 1 to 20 μm, more preferably 3 to 15 μm, more preferably from 5 to 15 μm.

The main body 12 may also be formed in multiple layers and have different shapes. In particular, it may have an additional stop layer / base layer of nickel or copper.

example 1

As an example of the coating of a printing cylinder 12 with a diameter of 60 cm, the first layer 14 has a thickness of 30 microns and consists of pure nickel with a mass fraction of 1.00, and the second layer 16 has a thickness of 5 microns and consists from a composition of nickel with a mass fraction of 0.96 and phosphorus with a mass fraction of 0.04.

Example 2

As another example of the coating of a printing cylinder 12 with a diameter of 80 cm, the first layer 14 has a thickness of 35 μm and consists of a composition (alloy) of nickel with a mass fraction of 0.96 and chromium with a mass fraction of 0, 04, and the second layer 16 has a thickness of 5 microns and consists of a composition of nickel with a mass fraction of 0.911, chromium with a mass fraction of 0.039, and hexagonal boron nitride with a mass fraction of 0.05.

The metallic constituent of the second layer 16 here has a mass fraction of 0.911 (nickel) + 0.039 (chromium) = 0.95, and based on the metallic constituent, that is without consideration of the non-metallic constituents, has Nickel has a mass fraction of 0.911 / 0.95 = 0.959 and the chromium has a mass fraction of 0.039 / 0.95 = 0.041, and this essentially corresponds to the mass fractions of the metals in the first layer 14. The mass ratio of chromium to nickel in the second Layer at 0.0428 (calculated by 0.039 / 0.911) substantially the same as in the first layer at 0.042 (calculated by 0.04 / 0.96). This has the advantage that after a removal of the first layer 14 and second layer 16, the removed material can be reused after cleaning of the additives, since the relative ratio of the mass fractions of the individual metals to each other (here nickel and chromium, possibly also additional Metals) in both layers is similar or substantially the same or the same. As is known to those skilled in the art, the metal content in the electrolytic baths will vary over time, and the concept of equality of the relative ratios of the proportions by weight of the individual metals to one another must be construed correspondingly wide.

Fig . 2 shows an enlarged view of the printing cylinder 10 with a cup 22 which extends through the second layer 16 into the first layer 14 and filled with ink 20.

The second layer (NiX layer) 16 also has the advantage of poorer wetting compared to pure nickel in addition to the better anti-wear properties, so that the printing ink 20 does not get stuck in the wells 22.

The cups 22 can be produced by engraving, in particular laser engraving and - if not too high hardness of the second layer 16 and / or a thin second layer 16 - by electromechanical engraving.

A great advantage of the second layer (NiX layer) 16 and also the first layer 14 is the good suitability for laser engraving. Especially with respect to the chromium and copper layers which are customary today, better results can be achieved in laser engraving in nickel.

manufacturing

Fig . 3 1 shows a galvanizing plant 50 with an upper trough 52, in which the gravure cylinder 10 is rotatably mounted, a first lower trough 54 with a galvanic nickel bath 55, and a second lower trough 56 with a galvanic NiX bath 57.

An anode cage 60 is partially disposed about the gravure cylinder 10 and connected to a voltage or current source 62, which is also connected to the gravure cylinder 10.

A pumping device 70 allows the bath 55 to be pumped into the upper trough 52, and a valve 72 allows the bath to be drained from the upper trough 52 into the first lower trough 54. Similarly, a pumping device 80 allows the bath 57 to be pumped into the first trough 54 Upper trough 52, and a valve 82 allows draining the bath from the upper trough 52 into the second lower trough 56th

In the illustrated method step, the nickel bath is pumped in the circuit via the pumping device 70 into the upper trough 52 and then discharged via the valve 72 back into the first lower trough 54.

The electroplating of the gravure cylinder 10 with the first layer 14 of nickel, e.g. with a relatively high deposition rate of, for example, up to 10 microns / min is possible, so that a layer thickness of 50 microns requires about 5 minutes. Subsequently, the nickel bath is completely discharged via the valve 72 into the first lower trough 54, and then the NiX bath from the second lower trough 56 is likewise pumped into the upper trough 52 in the same way, and the coating of the gravure cylinder 10 with the second layer 16 of NiX takes place. Here, the deposition rate is lower, for example, up to 5 μm / min, but the second layer 16 is thinner than the first layer 14, so that the entire coating of the gravure cylinder 10 with the first and second layers can take about 7 to 30 minutes.

A speed advantage is also achieved in that the same upper tray 52 can be used for both layers, since in both process steps a galvanic bath 55, 57 is used with the metal nickel and so impurity of the baths with foreign metals is excluded, which would normally require the use of two separate upper trays and a transport of the gravure cylinder 10.

After coating, the gravure cylinder is usually polished before the engraving is subsequently performed.

recycling

In order to be able to use the gravure cylinder 10 again, e.g. In the case of an adherent coating, the second layer 16 is completely turned off and the first layer 14 is partially turned off or milled on a lathe, and then a new coating can take place.

A major advantage of using the same metal or the same metal combination for the first and second layers 14, 16 is that the separated material - possibly after a cleaning process - can be used again for coating and no consuming or in part impossible separation of different metals must be done.

Fig. 4 shows a cross section through a gravure cylinder 10, in which between the base body 12 and the first layer 14, a release layer 13 is arranged.

The separating layer 13 serves to prevent a firmly adhering connection between the first layer 14 and the main body 12, so as to allow mechanical breaking and subsequent stripping of the first layer 14 and second layer 16 in the manner of a ballard skin.

As a separation layer 13, for example, a silver layer can be applied, which oxidizes, or an organic layer (eg, protein) can be used. The thickness is eg a few angstroms (1 Å = 10 ^-10 m).

NiH-BN

Fig. 5 shows a transverse section through a workpiece 10 with a base body 12 made of copper (copper bolt), on the surface 15 an outer, 60 micron thick layer (wear protection layer) 16 is applied, which consists of a composition of nickel and hexagonal boron nitride (h-BN) , The hexagonal boron nitride is visible in the form of dots 17, which are darker than the nickel. By contrast, the larger, very dark dots 24 are superficial deposits that have been added in connection with the creation of the cross section.

Above the Ni h-BN layer 16, a protective layer 19 of a potting agent (e.g., plastic) is applied, which is provided only to prevent destruction of the outer layer 16 in cross-section. The protective layer 19 and the main body 12 have been lightened by image processing for better reproduction.

Fig. 6 shows a cross-section through a Ni h-BN layer 16, the opposite to the layer 16 of Fig. 5 has a higher mass fraction of hexagonal boron nitride 17, recognizable as darker spots. The grooves 25 come from the cross section. Image editing has increased brightness and contrast. A scale is not available.

Fig. 7 shows the cross section Fig. 5 in the original.

Experiments have shown that such a Ni h-BN layer has very good anti-wear properties and therefore can be used in the coating of gravure cylinders as a replacement for a wear protection layer of hard chrome.

The hardness is approximately 450 to 600 HV 0.05, similar to a NiP layer, but less than that of hard chrome (up to 1200 HV 0.05).

A major advantage of the Ni h-BN layer is a large reduction in friction coefficient (friction coefficient reduction, friction coefficient reduction), in particular in the reduction of dry friction, wherein the friction coefficient reduction leads to Reduction of dry friction, whereby the friction coefficient reduction leads to the fact that the wear protection properties - depending on the application - are similar to hard chrome. In case of lack of lubrication occurs in tribologically stressed pure nickel quickly scuffing, and this is prevented by the achieved by the Ni h-BN layer friction coefficient reduction or at least reduced. The advantage of good coefficient of friction reduction is more important in terms of scuffing than the disadvantage of lower hardness. It is advantageous to add further particles such as SiC.

The mass fraction of the hexagonal boron nitride 17 in the layer 16 is preferably between 0.001 and 0.08, more preferably between 0.002 and 0.07, and more preferably between 0.01 and 0.05.

Preparation of Ni h-BN

• 500 g/l Nickelsulfat (NiSO₄ · 7 H₂0)
• 30 - 45 g/l Borsäure (H₃BO₃)
• 15 - 35 ml/l organischer Kornverfeinerer/Härtebildner, z.B. Saccharin
• 10 - 50 ml/l Zusatz, z.B. h-BN und/oder weitere Zusätze.

The production of a Ni h -BN layer was successfully carried out by a galvanic coating with the following bath batch:

• 500 g / l nickel sulfate (NiSO ₄ .7 H ₂ O)
• 30-45 g / l boric acid (H ₃ BO ₃ )
• 15 - 35 ml / l organic grain refiner / hardener, eg saccharin
• 10 - 50 ml / l additive, eg h-BN and / or other additives.

Since the hexagonal boron nitride does not dissolve in the bath, it is advantageous to use a ready-to-use aqueous h-BN suspension with a wetting agent, as it is commercially available, in the manufacture of the plating solution, and the plating bath must be present during the plating process Movement be offset. In experiments, a nickel content in the electrolytic bath of about 110 g / l and a pH in the range of 1.7 to 4.5 has proved to be advantageous.

It is also possible to speak of a dispersion layer in the case of a Ni h-BN layer or in another layer deposited from an aqueous dispersion.

The specified bath batch can also be used for the other mentioned NiX layers, the respective X content being added as an additive at the desired concentration.

Example 3

• 300 g/l Nickelsulfat
• 40 g/l Borsäure
• 2,6 g/l Saccharin
• 20 g/l h-BN

A well-adherent Ni h-BN layer on a degreased, activated and dekapierten copper stud has resulted in the following bath composition:

• 300 g / l nickel sulphate
• 40 g / l boric acid
• 2.6 g / l saccharin
• 20 g / l h-BN

The stated solids were dissolved in water. The temperature was 60 ° C. and the pH was 2. The electroplating program for 2 minutes was 2.5 A / dm ² for a smooth layer and then 10 minutes at 30 A / dm ² (depending on the desired layer thickness). ,

Naturally, various modifications and modifications are possible within the scope of the present invention.

A gravure cylinder preferably has an outer layer 16, in which nickel with a mass fraction of at least 0.85 and hexagonal boron nitride 17 are provided.

Preferably, the outer layer 16 comprises nickel with a mass fraction of at least 0.95.
Preferably, the outer layer 16 serves as a wear protection layer
Preferably, the outer layer 16 is electrodeposited.
Preferably, the outer layer 16 is deposited from an aqueous dispersion.
Preferably, the outer layer 16 contains silicon carbide.
Preferably, the outer layer 16 contains phosphorus.
The outer layer 16 preferably contains hexagonal boron nitride 17 with a mass fraction of between 0.001 and 0.08, preferably between 0.002 and 0.07, more preferably between 0.01 and 0.05.

Claims (14)

1. Gravure cylinder (10) which comprises:

   a base body (12),

   a first layer (14) which is arranged at least in part on the base body (12) and comprises nickel in a mass fraction of at least 0.80, in particular of at least 0.95,

   and a second layer (16) which is arranged at least in part on the side of the first layer (14) opposite the base body (12) and which comprises nickel in a mass fraction of at least 0.70, in particular of at least 0.85, and at least one non-metallic constituent,

   wherein the thickness of the first layer (14) is from 30 µm to 200 µm,

   wherein the thickness of the second layer (16) is from 1 µm to 20 µm, and

   wherein the second layer (16) is harder than the first layer (14),

   wherein the total non-metallic constituent of the second layer (16) has a mass fraction of from 0.001 to 0.15,

   and wherein the gravure cylinder (10) has at least in the second layer (16) cells (22) which are produced by laser engraving.
2. Gravure cylinder according to claim 1, wherein the non-metallic constituent comprises phosphorus (P).
3. Gravure cylinder according to claim 1 or 2, wherein the first layer (14) is thicker than the second layer (16).
4. Gravure cylinder according to any one of the preceding claims, which comprises cells (22) which extend through the second layer (16) into the first layer (14).
5. Gravure cylinder according to any one of the preceding claims, wherein the thickness of the second layer (16) is from 3 to 15 µm.
6. Gravure cylinder according to any one of the preceding claims, wherein the metallic constituent of the first layer (14) and of the second layer (16) in each case comprises nickel in a mass fraction of at least 0.95, in particular of at least 0.98.
7. Gravure cylinder according to any one of the preceding claims, wherein the metallic constituent of the first layer (14) and of the second layer (16) comprises at least one identical further metal in addition to nickel.
8. Gravure cylinder according to claim 7, wherein the relative ratio by mass between the mass of the at least one identical further metal and the mass of the nickel is substantially the same in both layers.
9. Gravure cylinder according to any one of the preceding claims, wherein the first layer and the second layer are electrodeposited.
10. Gravure cylinder according to any one of the preceding claims, wherein the entire non-metallic constituent of the second layer has a mass fraction of from 0.003 to 0.12, preferably from 0.01 to 0.10.
11. Gravure cylinder according to any one of the preceding claims, wherein there is arranged between the base body (12) and the first layer (14) a separating layer (13) which counteracts a strongly adherent bond between the first layer (14) and the base body (12).
12. Gravure cylinder according to any one of claims 1 to 10, wherein the first layer (14) and the second layer (16) are bonded firmly to the base body (12).
13. Gravure cylinder according to any one of the preceding claims, wherein the non-metallic constituent comprises silicon carbide (SiC).
14. Gravure cylinder according to any one of the preceding claims, wherein the non-metallic constituent comprises hexagonal boron nitride (h-BN).

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