Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
  • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
• • 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
  • B41N1/04—Printing plates or foils; Materials therefor metallic
  • B41N1/08—Printing plates or foils; Materials therefor metallic for lithographic printing
  • B41N1/083—Printing plates or foils; Materials therefor metallic for lithographic printing made of aluminium or aluminium alloys or having such surface layers
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/32—Alkaline compositions
  • C23F1/36—Alkaline compositions for etching aluminium or alloys thereof
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
  • C23G1/22—Light metals

Definitions

• the present invention relates to an aluminum alloy support for lithography. More particularly, the present invention relates to an aluminum alloy support for litho­graphy which can be electrochemically roughened to provide a roughened surface having a uniform appearance and excellent fatigue resistance, heat softening resistance, and printing durability.
• Conventional lithographic printing plates are generally obtained by subjecting an aluminum alloy sheet to a surface treatment such as roughening and anodic oxidation, coating a light-sensitive material on the aluminum alloy sheet, drying the light-sensitive material to form a PS plate, and then subjecting the PS plate to a plate-making process such as by imagewise exposure to light, development, and gumming-up treatment.
• a surface treatment such as roughening and anodic oxidation
• a light aluminum alloy plate excellent in surface-treatability, workability, and corro­sion resistance As a support for such a lithographic printing plate there is generally employed a light aluminum alloy plate excellent in surface-treatability, workability, and corro­sion resistance.
• Examples of such an aluminum alloy mate­rial include aluminum alloy plates having a thickness of 0.1 to 0.8 mm specified by JIS A 1050 (Al alloy having a purity of at least 99.5 wt%), JIS A 1100 (Al alloy comprising 0.05 to 0.20 wt% of Cu), and JIS A 3003 (Al alloy comprising 0.05 to 0.20 wt% of Cu and 1.5 wt% of Mn) (the term "JIS” as used herein refers to a "Japanese Industrial Standard).
• JIS Japanese Industrial Standard
• These aluminum alloy plates are roughened by at least one of mechanical, chemical and electrochemical roughening process­es, and then are subjecged to anodic oxidation.
• Such aluminum lithographic printing plates include an aluminum lithographic printing plate obtained by a process including mechanical roughening, chemical etching, and anodic oxidation as described in Japanesr Patent Application (OPI) No. 49501/73 (the term "OPI” as used herein means an "unexamined published Japanese patent application”); an aluminum lithographic printing plate obtained by a process including chemical etching, and anodic oxidation as described in Japanese Patent Application (OPI) No. 61304/76; an aluminum lithographic printing plate obtained by a process including electrochemical processing, after-treatment, and anodic oxidation as described in Japanese Patent Application (OPI) No.
• Aluminum alloy plates according to JIS A 1050 can provide a unform roughened surface or suitable surface-­roughness when subjected to an electrochemical roughening process.
• the non-image part on such a roughened surface is less susceptible to stain during printing.
• such aluminum alloy plates can provide excellent printing durability.
• such aluminum alloy plates are disadvantageous in that they have poor fatigue resistance and poor heat softening resistance.
• aluminum alloy plates according to JIS A 3003 provide sufficient fatigue resistance and sufficient heat softening resistance.
• such aluminum alloy plates are disadvantageous in that they cannot provide a uniform roughened surface or properly roughened surface when subjected to an electrochemical roughening process.
• Such aluminum alloy plates are also disadvantageous in that they are susceptible to stain of the non-image parts during printing.
• an aluminum alloy support for lithography having excellent printing durability, sufficient fatigue resistance and good heat softening resistance; that is capable of providing a uniformly and properly roughened surface when subjected to a roughening process, particularly an electrochemical roughening process; and that has low susceptibility to stain of the non-image parts during printing.
• the present invention provides an aluminum alloy support containing Mg in an amount of 0.3 to less than 1.0 wt%, preferably 0.5 to less than 1.0 wt%; Si in an amount of more than 0.3 up to 1.3 wt%, preferably from more than 0.3 up to 0.6 wt%, Cu in an amount of 0.003 to 0.10 wt% preferably 0.003 to 0.03 wt%; and the balance being Al and impurities.
• the average width of grain perpendicular to the rolling direction is at most 40 ⁇ m, preferably at most 30 ⁇ m.
• Mg is an element effective for improving strength, handling properties, and fatigue strength, and to provide a finely and uniformly roughened surface by electrochemical roughening process. If the Mg content is less than 0.30 wt%, these effects are in­sufficient. On the contrary, if the Mg content is 1.0 wt% or more, the electrochemically roughened surface can be non-­uniform. Therefore, the Mg content of the present aluminum alloy support for lithography is in the range of 0.30 wt% to less than 1.0 wt%.
• Si is an element effective for obtaining finely and uniformly roughened surface by electrochemical roughening process. Si also con­tributes to improvement in strength by combining with Mg. If the Si content is 0.3 wt% or less, these effects cannot be sufficient. On the contrary, if the Si content is more than 1.3 wt%, the electrochemically roughened surface can be nonuniform and large elemental Si constituents result in stain during printing. Therefore, the Si content of the present aluminum alloy support is in the range of more than 0.3 up to 1.3 wt%.
• Cu is an element effective for improving strength and making finely and uniformly roughened surface by electrochemically roughening process. If the Cu content is less than 0.003 wt%, these effects are not sufficient. On the contrary, if the Cu content exceeds 0.10 wt%, the diameter of pits in the electrochemically roughened surface tends to be large and the surface is nonuniform. Therefore, the Cu content of the present aluminum alloy support is in the range of 0.003 wt% to 0.10 wt%.
• Cr may be optionally present in the aluminum alloy if desired. Cr is effective for improving strength, and refining recrystallized grain and producing fine and uniform electrochemically roughened sur­face by electrochemical roughening process. However, when the Cr content is more than 0.25 wt%, large intermetallic compounds (A3Cr) are crystallized in casting, causing defects on the surface of the aluminum alloy plate. Therefore, if Cr is present in the aluminum alloy as necessary, its contents preferably at most 0.25 wt%, and more preferably 0.05 wt% to 0.25 wt%.
• A3Cr intermetallic compounds
• aluminum alloys contain Fe as an un­avoidable impurity.
• the Fe content is preferably limited to 0.50 wt% or less, particularly 0.30 wt% or less. Fe is effective for improving strength and fatigue strength. How­ever, if the Fe content exceeds 0.50 wt%, large intermetal­lic compounds of an Al-Fe-(Si) system are formed, providing a nonuniform electrochemically-roughened surface. This also renders the aluminum alloy plate more susceptible to stain during printing, and is the reson why the Fe content is preferably about 0.50 wt% or less.
• the content of im­purities other than Fe may be near the value used in commer­cially available industrial pure aluminum.
• Ti or Ti-B is added as a grain refiner.
• the present aluminum alloy support for lithography optionally may contain Ti and/or B as a grain refiner of ingot.
• the Ti content and the B content are preferably at most 0.1 wt% and 0.02 wt%, and more preferably 0.005 wt% to at most 0.1 wt% and 0.0005 wt% to 0.02 wt%, respectively.
• impurities which may be contained in the alloy of the present invention are, for example, at most 0.15 wt% of Zn, at most 50 ppm of Be and at most 0.15 wt% of Zr, Vand Mn.
• the average width of grain (in the direction) perpendicular to the rolling direction is 40 ⁇ m or less, more preferably at most 30 ⁇ m.
• the grain size obtained at inter­mediate annealing before final cold rolling step must be at most 40 ⁇ m.
• the minimum average width of grain perpendicular to the rolling direction smaller one is preferred, but it is generally difficult to produce grains having 5 ⁇ m or less of the average width of grain in manufacturing. In other words, the fine grains allow the aluminum alloy support to be better roughened. Thus, a substrate for a printing plate support having an excellent external appearance can be obtained.
• the average width of grain is measured by intercept procedure.
• a molten aluminum alloy containing the above mentioned components is subjected to any ordinary casting process.
• the casting may be accomploished by a semi-continuous casting process.
• continuous sheet casting may be effected.
• the resulting ingot is subjected to homogenization, hot rolling, cold rolling, intermediate anneal­ing asn so on to obtain a sheet having preferably a thickness of 0.10 to 0.50 mm, more preferably 0.15 to 0.35 mm.
• the homogenization treatment is preferably conducted at a tem­preature of 450 to 610°C for 1 to 48 hours so that the grain size are fine at intermediate annealing and non segregation of Fe, Si, Mg in the ingot occurs to obtain a uniform distri­bution of the components, and thereby the aluminum alloy support is uniformly roughened when subjected to electro­chemical etching.
• the heat treatment for the homogenization and the hot rolling process can be conducted in two stages or one stage. In any case, the hot rolling preferably begins at a temperature of 400 to 550°C.
• the aluminum alloy support is generally subjected to a first cold rolling, inter­mediate annealing, and then a final cold rolling.
• two or more intermediate annealing steps may be conducted between the first cold rolling and the final rolling steps.
• the intermediate annealing temperature is preferably in the range of 300 to 600°C for at most 5 hours.
• the intermediate annealing may be either an ordinary batch annealing (average heating rate: 20 to 50°C/hr) or a continous annealing (average heating rate: a few degree c/sec. to several tens of degrees c/sec.). In order to make the average grain size before final cold rolling at most 40 ⁇ m or less, continuous annealing is preferably used rather than batch annealing.
• Continuous annealing is also preferably effected in order to improve strangth by precipitation of Mg2Si.
• the intermediate annealing temperature is preferably 380°C or above for recrystallization, more preferably 380°C to 550°C, most preferably 450°C to 550°C in order to improve strength by precipitation of Mg2Si.
• the soaking temperature is preferably higher than the ordinary temperature in order to obtain finer recrystallized grains.
• the intermediate annealing conditions are important in making the average grain size of 40 ⁇ m or less.
• the larger cold reduction ratio is preferred, but in practically the maximum reduction ratio is about 95%, in a manufacturing technique and in considering a characteristics of support for a lithographic printing plate.
• the final cold rolling needs to be conducted at a cold reduction ratio sufficient to provide a proof stress of 15 kgf/mm2 is obtained.
• the cold reduction ratio at the final cold rolling needs to be at least 20%, more preferably at least 30% and most preferably at least 40%.
• the larger cold reduction ratio is preferred, but in practically the maximum reduction ratio is about 95%, in a manufacturing technique and in considering a characteristics of support for a lithographic printing plate.
• the temper may be any one of H1n, H2n, and H3n (alloys which are not subjected to heat treatment and defined in JIS H 0001) so long as a proof stress of at least 15 kfg/mm2 can be obtained.
• Examples of graining processes which can be used in the present invention include an electrochemical graining process by electrochemically roughening the material in a hydrochloric acid or nitric acid electrolyte; and a mechanical graining process such as a wire brush graining process which includes scratching the surface of aluminum with a metal wire, a ball graining process which includes roughening the surface of aluminum with abrasive balls and abrasive agents; and a brush graining process which includes roughening the surface of aluminum with a nylon brush and an abrasive agent.
• These graining processes may be used, singly or in combination.
• the electrochemical etching process is advantageous in that it provides a uniformly and properly roughened surface. It is also advantageous in that the non-­image parts thus obtained is less susceptible to stain during printing.
• the aluminum thus roughened or grained is then chemically etched with an acid or alkali. It takes a longer time to destroy the fine structure by acid etching, therefore, in general, it is desirable that an alkali be used as an etching agent.
• concentration of such an alkali agent is preferably in the range of 1 to 50 wt% based on an etching solution.
• the temperature of such an alkali agent is preferably in the range of 20 to 100°C.
• the condition of such an alkali agent is preferably such that aluminum is dissolved in an amount of 5 to 20 g/m2.
• the aluminum After being etched, the aluminum is normally washed with an acid to remove remaining contaminants (smut) from the surface thereof.
• an acid which can be used in this washing process include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and boro­fluoric acid.
• the removal of smut after the electrochemical roughening process is preferably accomplish­ed by a process as described in Japanese Patent Application (OPI) No. 12739/78 which includes bringing the material into contact with a 15 to 65 wt% sulfuric acid solution at a temperature of 50 to 90°C, or a process as described in Japanese Patent Publication No. 28123/73 which includes etching with an alkali.
• the aluminum alloy plate thus processed can be used as a support for lithography.
• the aluminum alloy plate may be further subjected to a processing step such as anodic oxidation, if desired.
• the anodic oxidation can be accomplished by any suitable method which has been heretofore used in this field.
• the aluminum alloy plate may be pro­cessed in an aqueous or nonaqueous solution of sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, or benzenesulfonic acid, or a combination thereof with a d.c. or a.c. current passing therethrough so that an anodized film is formed on the surface thereof.
• the conditions of the anodic oxidation depend on the electrolyte used and cannot be specifically defined.
• the anodic oxidation is preferably effected at an concentration of 1 to 80 wt% of electrolyte based on an electrolytic solution, an electrolyte temperature of 5 to 70°C, and a current density of 0.5 to 60 A/dm2 on 1 to 100 V for an electrolysis time of 10 to 100 seconds.
• Preferred examples of such an anodic oxidation process include a process as described in British Patent 1,412,768, which includes anodic oxidation with a high current density in sulfuric acid, and a process as described in U.S. Patent 3,511,661, which includes anodic oxidation in phosphoric acid as an electrolytic bath.
• the aluminum alloy plate thus anodized may be fur­ther subjected to a processing step as described in U.S. Patents 2,714,066 and 3,181,461, which includes dipping the aluminum in an aqueous solution of metallic silicate such as sodium silicate, or a processing step as described in U.S. Patent 3,860,426, which includes applying an undercoat layer of a hydrophilic cellulose (e.g., carboxymethyl cellulose) containing a water-soluble metallic salt (e.g., zinc acet­ate) on the aluminum alloy support.
• a hydrophilic cellulose e.g., carboxymethyl cellulose
• a water-soluble metallic salt e.g., zinc acet­ate
• Any conventional light-sensitive layer which has been heretofore known as a light-sensitive layer for a PS plate may be coated on the lithographic aluminum alloy sup­port according to the present invention to obtain a light-­sensitive lithographic plate.
• Such a light-sensitive litho­graphic plate can then be subjected to any conventional plate-making process to obtain a lithographic plate having excellent properties.
• a product of condensation of a diphenylamine-p-­diazonium salt as described in U.S. Patents 2,063,631 and 1,667,415 (the product of the reaction of a diazonium salt with an organic condensing agent containing a reactive car­bonyl group such as an aldol and an acetal) with formalde­hyde ("light-sensitive diazo resin") is preferably used.
• organic condensing agent containing a reactive car­bonyl group such as an aldol and an acetal
• formalde­hyde formalde­hyde
• Other useful examples of condensed diazo compounds are dis­closed in Japanese Patent Application (OPI) Nos. 48001/74, 45322/74 and 45232/74.
• Such light-sensitive diazo compounds can be normally obtained in the form of a water-soluble inorganic salt and thus can be coated on a support in the form of an aqueous solution.
• these water-soluble diazo com­pounds may be reacted with an aromatic or aliphatic compound containing one or more phenolic hydroxyl groups and/or sulfonic acid groups in a process as disclosed in Japanese Patent Publication No. 1167/72.
• This reaction produces a substantially water-insoluble light-sensitive diazo resin which can be used in the present light-sensitive layer.
• these water-soluble diazo compounds can be used as products of reaction with hexafluorophosphate or tretra­fluoroborate.
• Diazo resins as described in British Patent 1,312,925 may be preferably used.
• Such an o-­quinonediazide compound include an o-naphthoquinonediazide compound.
• suitable o-naphthoquinonediazide com­pounds are described in U.S. Patents 2,766,118, 2,767,092, 2,772,972, 2,859,112, 2,907,665, 3,046,110, 3,046,111, 3,046,115, 3,046,118, 3,046,119, 3,046,120, 3,046,121, 3,046,122, 3,046,123, 3,061,430, 3,102,809, 3,106,465, 3,635,709, and 3,647,443.
• Examples of such a light-sensitive layer composition include a composition containing an azide compound as de­scribed in British Patents 1,235,281 and 1,495,861, and Japanese Patent Application (OPI) Nos. 32331/76 and 36128/76 and a water-soluble or alkali-soluble high molecular com­pound, and compositions containing a polymer containing an azide group as described in Japanese Patent Application (OPI) Nos. 5102/75, 84302/75, 84303/75 and 12984/78 and a high molecular compound as a binder.
• OPI Japanese Patent Application
• Other useful light-sensitive resin layer composi­tions include polyester compounds as disclosed in Japanese Patent Application (OPI) No. 96696/77 polyvinyl cinnamate resins as described in British Patents 112,277, 1,313,309 1,341,004 and 1,377,747, and photopolymerizable photopoly­mers as described in U.S. Patents 4,072,527 asnd 4,072,528.
• OPI Japanese Patent Application
• the amount of the above light-sensitive compositions in the light-sensitive layer to be formed on the support is 0.2 to 7.0 g/m2, preferably 0.5 to 4 g/m2.
• the PS plate After being imagewise exposed to light, the PS plate is subjected to any conventional processing steps including development so that a resin image is formed.
• the unexposed portion of the light-sensitive layer is removed by development to obtain a lithographic plate.
• the unexposed portion is removed by develop­ment with an alkaline aqueous solution to obtain a litho­graphic plate.
• the alloy specimens A to E shown in Table 1 were casted by DC casting and scalped on both sides thereof to obtain alloy ingots 500 mm thick, 1,000 mm wide, and 3,500 mm long. These ingots were then subjected homogeniza­tion at a temperature of 560°C for 10 hours. These ingots thus homogenized were heated to a temperature of 480°C and then hot-rolled to 4 mm thick plates. These alloy plates were cold-rolled to 1.5 mm thick plates. These alloy plates were intermediate-annealed at a temperature of 470°C in a continuous annealing process. These annealed alloy plates were then cold-rolled to 0.3 mm thickness. These aluminum alloy plates were evaluated for electrolytic etching proper­ties, appearance of roughened surface, fatigue strength, heat softening resistance, and printing durability by the methods specified below. The results are shown in Table 2.
• the surface condition of the specimens was observed by means of a scanning electron microscope to evaluate the uniformity of pitting. Excellent uniformity is indicated by the symbol ⁇ . Good uniformity is indicated by the symbol ⁇ . Poor uniformity is indicated by the symbol X.
• the surface appearance of the aluminum alloy sup­ports for lithography after anodization by the undermention­ed method (5) was visually judged for streaks and unevenness in color tone.
• Streaks are marks developed in the rolling direction due to nonuniformity in chemical etching or elec­trolytic etching or nonuniformity in the micro-structure of aluminum alloy sheet.
• the condition without streaks is indicated by the symbol ⁇ , and the condition of many streaks is indicated by the symbol X.
• the condition of nonuniform color tone on the roughened surface, or poor evenness, is indicsated by the symbol X.
• the condition of uniform color tone, or excellent evenness is indicated by the symbol ⁇ .
• the appearance of both streaks and unevenness is undesirable for aluminum alloy supports for lithography.
• a tensile load of 5 Kgf/mm2 was repeatedly applied at a frequency of 25 Hz to one end of specimens which had been bent at 2 mm radius with right - angle until the specimens were broken.
• the number of repetitions of stress before breakage represents the fatigue strength of the specimens. In practical use, this value is preferably 80,000 or more.
• the specimens were heated to a temperature of 270°C for 7 minutes in Burning Processor Model 1300 (Fuji Photo Film Co., Ltd.'s burning processor equipped with a 12-kw heat source). After being allowed to cool, the specimens were measured for proof strength to evaluate their heat softening resistance.
• Printing plates which had been subjected to the undermentioned processing were mounted in an offset printer KOR (made by Heidelberg Co.). After being printed, the printing plates were evaluated for strain of the non-image parts.
• the printing plates used were prepared in the fol­lowing manner:
• the aluminum alloy plates used were roughened with a rotary brush in a suspension of pumice and water.
• the aluminum alloy plates thus processed were then etched with a 20 wt% aqueous solution of caustic soda based on an etching solution in such a manner that the aluminum was dissolved in the solution in an amount of 8 g/m2.
• the aluminum alloy plates thus etched were thoroughly washed with running water, then washed with a 25 wt% aqueous solution of nitric acid, and then washed with water.
• the specimens thus prepared were coated with the following light-sensitive layer composition in an amount of 2.5 g/m2.
• Ester compound of naphthoquinone-1,2-­diazide-5-sulfonylchloride with a pyrogallolacetone resin (as described in Example 1 in U.S. Patent 3,635,709) 0.75 g Cresol novolak resin 2.00 g Oil Blue + 603 (Orient Kagaku) 0.04 g Ethylene dichloride 16 g 2-Methoxyethylacetate 12 g
• These light-sensitive lithographic plates thus prepared were imagewise exposed to light from a 3-kw metal halide lamp placed at a distance of 1 meter therefrom for 60 seconds, developed with an aqueous solution of sodium sili­cate having an SiO2/Na2O molar ratio of 1.2 and containing 1.5 wt% of SiO2, washed with water, dried, and then rubbe­rized.
• the present alloy specimens A and B both had a high fatigue strength as well as excellent heat softening resistance, electrolytic etching properties, surface appearance, and printing durability.
• the comparative alloy specimen C exhibited poor fatigue strength as well as poor heat softening resistance.
• the comparative alloy specimens D and E had poor elec­trolytic etching properties, surface appearance, and printing durability.
• Ingots of the alloy specimen B shown in Table 1 were processed under various preparation conditions so that 0.3-­mm thick aluminum alloy plates having different width of grain were obtained. These aluminum alloy plates were evaluated for electrolytic etching property, surface appearance, fatigue strength, heat softening resistance, and printing durability as in Example 1.
• Table 3 shows the various preparation conditions and the average width of the grain perpendicular to the rolling direction.
• Table 4 shows the results of the evaluation.
• the plates prepared under conditions producing an average width of the grain perpendicular to the rolling direction of 40 ⁇ m or less had a high fatigue strength as well as excellent heat softening resistance, electrolytic etching properties, surface appear­ance, and press life.
• the preparation conditions 2 and 3 too high intermediate annealing tempera­ture is employed (in condition 2) and the cold reduction ratio provided by a cold rolling before intermediate anneal­ing is too low (in conditions 2 and 3), the size of grains thus obtained is too large to obtain the aluminum sheet having superior surface appearance.
• the aluminum alloy supports for lithography of the present invention have a fatigue resistance and heat softening resistance that is sufficient for use as printing plate supports, as well as excellent electrolytic etching properties, which provide a uniformly and properly roughened surface, particularly when electro­chemically roughened. Furthermore, lithographic plates containing the present aluminum alloy support have excellent printing durability, and are less susceptible to stain of the non-­image portion. Thus, the present aluminum alloy plates are extremely excellent lithographic support.

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Citations (5)

• 1986
  • 1986-08-18 JP JP19224786A patent/JPS6347349A/ja active Pending
• 1987
  • 1987-08-18 EP EP87307277A patent/EP0257957A1/fr not_active Withdrawn

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