DE1671511A1 - Printing plates and processes for their manufacture - Google Patents

Description

DR.-INQ. DIPI INQ. M.SC. DIPL.-PHYS. DR. DIPL.-PHYS. HÖGER - LEGAL RIGHTS - GRIESSBACH - HAECKER PATENT LAWYERS IN STUTTQART

A 35 868 b h - te 17.8.67

U.S.Ser.Ho. 593,535

Sexaa Instruments Incorporated, B & llaa, Sex & e, U.S. A,

Printing plates and process for their Manufacture

The invention relates custody on printing plates and in particular to printing plates that have a structured zinc-based alloy ₀ which is then etched ,, namely Gate * sugsweise by so-called pulverloeea etching,

The main difficulty encountered when using τοη zinc * plates when etching and especially when etching powderless occurs in the unpredictable formation of so-called coils (pimple ·) in the worn out Depressions in the printing surfaces of these plates »These Piokel

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Bind is shown in Pig.5 and will be discussed below explained in more detail.

The Piokel are small, relatively pointed protrusions that are mechanically made by hand with a hand tool or a machine must be removed before a printing plate can be used in a printing press • If you do not remove these Yora protrusions from the ground, slota will result unwanted spots on the paper and thus an unsightly, messy appearance · The removal of these Piokel is very expensive, and besides that there is always di Risk of damage to the plate in such a way that it has to be thrown away. True, this difficulty occurs in general on all engraving plates, but it is the case with zinc print plates such as those used in photo engraving become particularly large. According to the present invention can the formation of these pillars be prevented or at least be reduced to a considerable extent so that the Printing plates consistently deliver clear, non-blurry prints,

A common zinc alloy for the production of zinc platea has about 0.06-0.14 * aluminum (Al), 0.00-0.20Jt Magneeiua (Ug) and the remainder zinc (Za). Aueeerdeo

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Certain spusmsn constituents are never present in impurities, for example iron, cadmium, copper or lead. An ingot, which can be several centimeters thick, is first cast in the form of a plate from a melt of such an alloy. The ingot is then rolled down after cooling and solidification on the printing plate Strong, for example, O ₉₈₁₃ or 'l _fl 62i5'mni ₀ These figures is the usual strengths as a Xtitiefe in-Platt · of about 0 ₀ 254 to 1.016 mm can be used

The invention is based on the object of creating sink alloy pressure plates that are relatively free of undesirable pimples. The task is with a pressure plate with at least one surface that is suitable for bridges after an etching process and in which the piekelbiiaende concretionea gate bands are solved by the fact that there are no more approximately two concretions per 6 ^ 2 cci ² (square xoli) of the surface within the observed etching depth to the desired extent _a

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Further advantages and advantages of the invention result From the following description in connection with the drawing, the Ausführungsbeiapitle of the invention contains. Show in the drawing «

Pig. 1 a schematic partial section for illustration

a first embodiment of a printing plate in FIG etched condition, which geotäse the process. represents is

Pig «2 shows a part information similar to Pig. 1 for explanation another embodiment of the invention,

Pig 3 cross-sections through Tersuohereinrichtungen ₉ to demonstrate certain cooling effects on zinc alloys,

Pig.4 is a picture-like, partially sectioned view to represent a casting process stage for Production of tine zinc ingot, as it is used for the · » Implementation of the invention is used «.

Figc5 is a partial section shown on a much larger scale, which is etched across a The plan of a known printing plate is laid out in order to explain the manner in which the disadvantages

gen pimples occur here, according to the invention should be avoided "

Pig.6 is a diagrammatic view for illustration GuBSververfahrenBohrittes, which in a different way than

genäse Pig.4 is carried out *

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Am sharp enlarged? The cross section of a rolled down and etched plate, which is produced according to the invention, is shown in Pig. 1 and denoted by 1. If necessary, the plate 1 can also be provided with a carrier layer 5 fastened by a composite, as shown in Fig. 2 is shown. This carrier layer can consist of aluminum, for example. The layers are preferably formed by a composite solid phase ISS miteinander'verbunden _f J but other Verbundverfahreη also be used ₉

Impurities and the special traces of iron are probably the main causes for the formation of the protrusion · « It is assumed that the iron particles distributed everywhere in the alloy melt produce low concretions, which are distributed over the whole mass of the bar when it cools down slowly After the bar has come down is rolled, a large number of these concrete items

en

nen on the surface of the plate or in dsr / ^ uh «, dVh. at a point where this «plate is then to be etched». When ^{etched, 1} d, ese concretions then cause the plokel. The ^ e concretions are very small, d _e h. 0.1 yu mean diameter approximately to 10, Bm was echwierig _t ztt determine what composition it have "concretions, but indications are dee vorhandta *" she

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also Bisen (Pe) see, Sisenoxyd CPe ₃ O ₅ ) or possibly some intermediate compound, such as IeAl ₂ , Ie ₃ Al ₅ or PeAl ₅ , it is assumed that such concretions in connection with the trace content of iron or arise from this content when the molten zinc alloy slowly hardens after the Tergieaen calibration and then takes the form of bars or blanks "

Eb was also found that by controlling the Trace ele content as an impurity in the zinc alloy and the rate of heat dissipation during the number of pimples as the cast ingot cools down a zizak plate on the printing surface or in its Häha at Orphans of the same can be reduced to such an extent that these pimples can no longer cause damage can form, and through a suitable rapid cooling the ability of the trace iron to form such concretions form, reduced. In the table below are some «contain the results of experiments that led to the invention. They show the effect of the iron content and the rate of heat dissipation from the solidifying Sarren in the formation of the concrete, which, how mentioned above, il * create foresight "

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Cabelle

2)

Number of concretions per bar 'area' tos approximately 18.06 cm ²

alloy
Iron content
(Parts per
Millioa}

5 or less
30-70

120 or more

Heat dissipation rate from the barrengues (Btu / lb. / seo.T

0.036 or less

10-15

21,000 27,000

30,000 40,000

0.144 to
0.432

0-10

000

000 000

1.44 or »or rather

0-10 0-10

10,000 15,000 (estimated)

1) This is a cast ingot, for example through Walstm and WäEL © beii & is «! lWf on eiae Strength Tos 2.032 to redusi @ rt

2 Bies means the area on the front face of the ingot which becomes the pressure surface of the pressure plate after ¥ & loosening .

BATH ORIGINAL

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The heat dissipation at the specified speeds can be achieved by pouring the alloy melt onto a cool surface. The cool surface forms the front surface of the ingot, which then, after rolling down, results in the printing surface of the printing plate. If a certain cooling rate is achieved on a cooling surface, the cooling speed is smaller at a distance from this surface. This will be on hand de? Infusion device according to FIG. 3 explained. In (a) of FIG. 3, a water-cooled, new copper-formed cooling block 5 is shown at the upper end of a layer 7 of a hardening zinc alloy, which is cooled in a vessel 8 with low thermal conductivity. In (b) of FIG. 3, the water-cooled iühlblook 5 is arranged on the bottom of a casting mold 9 of low thermal conductivity, Ea shows that in both cases (a) and ( ^b ) those responsible for the pokel formation (indicated by dots) Concretions do not exist or are reduced in number in the material which is closest to the cooling bloom. Although a cooling block cooled by a flow medium can be used without further ado, in a normal casting mold 9 for a melt 11 there can also be a bottom surface 12 which has a temperature gradient for the desired

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Abfculilgeeohwindiekeit results (see Fig. 4). I'm more typical ingots or a blank obtained from the melt 11 after cooling can be 2.40 m long, 55 cm wide and Be 65.5 mm thick «

Since the bottom 12 of the seating mold 9 acts as a coolant (if necessary, it can also be replaced by a tile medium), the bottom surface of the melt is cooled relatively rapidly this surface dee scaled completely solidified. Barrens or in their vicinity gives aioh the smallest "collection of concretions that produce foci, such as the" from the table above can be seen at the front 24 de «Barrens is therefore the least accumulation of concrete» options available. This side is then after rolling out the printing surface 13 of the plate and that indifferent, whether this plate is now according to Fig.l without a carrier layer or according to Pig, 2 is provided with a carrier layer 3 »

If the bar is thrown down, it is enlarged he his area. The area on the end face 14 with the low accumulation of concretions is thus larger As a result, the number of concretions per unit area of the pressure side 13 of the resulting plate is nooh less. The thickness of the ingot is chosen so that at

161140/030 BADORIGINAU

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The accumulation is achieved by the thickness of the printing plate desired γόη concretions on the printing surface of the printing plate or in its Sew about two concretions or less per square inch (6.2 cm) of the print area reached "Through the printout" on the Printing area of the printing plate or its height "is called the accumulation on the printing surface at a depth that is the same or slightly greater than the normal etching depth let.

From the table above it can be seen that with low iron ™ contamination in the zinc alloy, low accumulation of Pimples on the cooled surface of the ingot do not require a high rate of heat dissipation, as is the case for larger bise contents the Sail is. An iron content of no more than 5 ropes per million is therefore a speed for heat dissipation of the board of 0.036 Btu / lb. / sec. or less satisfactory, and a heat exit rate of 0.144 Btu / lb. / sec. or more results in as little accumulation (0-10) of pimples as can be achieved on the surface of the ingot, provided that the iron content is not greater than 70 Ropes per Hillion 1st. To an equally low number (0-10) from Pick one at an iron content that is greater than 30 -70 ropes per million, it is required that 1.44 Btu / lb. / eec, or more must be carried away · With an iron content of more than 120 ropes

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per million does not result in a practically usable speed for heat dissipation in order to achieve a sufficiently pimple-free surface. Preferably, according to the invention, in order to achieve the lowest pimple accumulation, the molten alloys should have an iron content of less than 70 ropes per Hillion, with the heat release rate during casting in the range between 0.144-0.482 Btu / lb. / seo for the greatest economy according to the invention. should lie. On the other hand constantly obtain ITm an optimally high quality of the zinc plate with a orsprungsfraien v substantially surface should according to the invention, the iron content is preferably less than 5 cables per Hillion at a heat dissipation rate of 1 ₀ 44 B-fcu / lb. / seo. or be more

The following are some of the relationships that exist

the parameters, namely the iron content and there-. Waste disposal

found favorable in practice.

Jüisengeha? .T heat dissipation compliance Ropes per from the parallel bars Hillion Btu / lb. / eeo »

0.001-3.00 0.001-0.035 0.035-1.44 1.44 or more

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Pig. 5 shows in a considerably enlarged Macstab a part of a typical printing surface of a known printing plate 15, which is made of gray zinc, without any corresponding relationship between the parameters, namely the iron content of the zinc melt and the rate of heat dissipation during solidification “Consideration was given. The pressure surfaces are denoted by 17 and the etched recesses are denoted by 19. Before etching around the plate a dense accumulation τοη concretions from the non-etched printing area was out all over the etch depth e existing The figured ze igt how the existing in the areas 19 before Xteen concretions affect the right Ktseη at 19 and pimples form, -she has hematically indicated at 21 «When coloring the non-etched print areas 17, part of the parbe reaches the tops of many of the higher pimples 21. When printing, this results in an unsightly, blurred area within the print image, because "is produced by the printing surfaces 17 * The work parts caught on the tips of the projections 21 reach the paper because the latter has a certain tendency to press into the etched recesses.19"

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As shown in FIGS. 1 and 2, the number of concretions within the etching depth E of the plates ep according to the invention is low, since very few or no pimples are formed in the etched recesses 20. The ideal case, namely that there are pimples within the etched-out recesses 20, is shown in Figures 1 and 2, "In practice it is still acceptable if in the recesses 20 about two or less protrusions" per square inch (measured are present on the pressure surface 13).

In this case, the cost of removing the projection « not unbearably high. The theories given above are, moreover, only one possible explanation entrusted to the invention and are by no means binding "

Instead of using the known batch energy to produce ingots (β. Fig. 4), continuous casting can also be carried out according to Fig. 6, in which 23 denotes a storage vessel made of refractory bricks for holding molten zinc 24. Sa «storage vessel 23 leads to a hollow, square-shaped box» 25, the four of which can have cooling channels «for« in «coolant. Two of these cannulas in two walls are shown schematically at 28 and 30, but similar channels can also be found in the other walls. With 29 lt

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marked downwards aurttckzlehbaren table that when raised the lower open end of the Kuhlfora 25 abeehlieast, The The withdrawal movement is indicated by an arrow 32 indicated. The table 29 has upstanding tabs 31, which pa3sen in the lower end of the cooling fora, if

β * this closed by the TIsoh 29 in the raised position will. These lobes are generally the first part of the Zintanasse anchored when the zinc solidifies in the KUhIform 25, which is then locked voa Tiaoh 29. Anachliesaend will the table 29 is continuously withdrawn to aea solidified part 29 subsequent parts of the tine «deduct, if theee üeilstücki through the cooling fora 25 hinduoh · happen and solidify there. This results in an alternate strand, 35 of unlimited length ... which is continuously formed and which is then later converted into certain bars

^ lengths can be divided. The shedding and solidification occurs essentially uniformly and simultaneously on .aämtliohen surfaces of the bar produced in this way. Since the ingot has now been rolled down to the thickness of the Druok slab, all surfaces are characterized by the absence of a considerable number of pimple-forming concretions. Any · * o formed · »puddle of the rolled plate can be used from ite» n. Hierdureh "rgibt" I ineofera "In practical Torteil, ale ee nioht necessary let that Plattenoberfläeae s" * _t enneeiohnen the shopping eels breathed the Brandon "has"

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Claims (12)

h-24 8/15/1967 claims 1. Printing plate with at least one after an etching process for Printing a suitable zinc alloy surface in which there are pebble concretions, characterized in that within the intended etch depth no more than about two concretions per 6.2 cm (per square inch) of surface area. 2.! Pressure plate with etched zinc alloy having Surface in which pimples are present in the depressions, characterized in that the number of pimples in the indentations no more than about two per 6.2 cm (per square inch) of surface area, 5 printing plate according to approach 1 δδ @ ϊ 2, characterized in that that the zinc alloy G * GC3 Ms 0.14 # Al »C% ^ Me 0.20 # Kg and the rest of zinc, with SpursKverurtreinigungen are neglected. 4. Zinc alloy for casting ingots, which can then be rolled out into glass material for printing plates »characterized in that the zinc alloy contains approximately 0 _f 06 to 0.014 $ Al, OfOO to 0.20 £ Mg and the rest of zinc and that as a setpoint Contamination up to 70 ropes per million is present. 5. Terfahren sum production of e-lining material for printing plates forming a melt of a zinc alloy, the - 15 - 109840/0301 BATH ORIGINAL A 35 868 h - November 2nd, 1967 then in an? orm sum producing an ingot »preferably in blank form, is poured, whereupon the ingot is placed on a yiach material in the shape required for printing plates and Starch is rolled down, especially naoh one of the Going claims, characterized in that the elsenic contamination in the melt is chosen to be at most as high and at least one surface of the melt and / or the ingot during solidification as much heat per Weight unit and time unit is withdrawn so that the number of concretions on the at least one surface of the flaoh material per unit area of the same up to the etching depth has the desired minimum value. 6. The method according to claim 5 »characterized in that the Iron contamination in the melt is chosen to be a maximum of 70 parts per Hillion. 7. The method according to claim 5 or 6, characterized in that that the number of concretions per unit area of the bar corresponding to the later Itz depth is at most about 15 amounts to. 8. The method according to any one of claims 5-7, characterized in that the number of concretions per 6.2 cm (per Square inch) of the surface of the flat materialβ to the etching depth is at most two. 9. The method according to any one of claims 5-8, characterized in that the heat dissipation with the corresponding amount takes place on one of the main flutes of the ingot. - 16 - 109840/0301 A 35 868 h - ♦ € - ^ h-2§ A * November 2nd, 1967 10. The method according to any one of claims 5-9 for casting Ingot, characterized in that the heat removal geeohwin * strength when the melt solidifies in the range between 0.001-300 Btu / lb. / sec. lies. 11. The method according to one of the Ansprttohe 5-10, characterized in that that the rate of heat dissipation when "solidifying the melt is at least 0.036 Btu / lb. / sec "is" 12. The method according to any one of claims 5 - 11 »characterized in that that the rate of heat dissipation when the melt solidifies is at least 0.144 Btu / lb. / sec. is. 13 »Method according to one of claims 5-12, characterized in that that the rate of heat dissipation when the melt solidifies is at least 1.44 Btu / lb. / sec »* 14 * Method according to one of claims 5-13 »characterized in that that the wax removal rate when solidifying the melt in the range between 0.144 and 0.482 Btu / lb. / sec. lies. 15 "Method according to one of claims 5-14" characterized in that that the iron contamination is at most five ropes per hillion. BATH ORIGINAL 108840/0308 Blank page