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
• • 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

Definitions

• the present invention relates to an aluminum alloy, a lithographic printing plate support and a lithographic printing plate using the same.
• This surface roughening treatment is called graining, and includes mechanical graining such as ball graining, sand blast graining or brush graining, electrochemical graining which is also called electrolytic polishing, and chemical etching which is called chemical graining.
• mechanical graining such as ball graining, sand blast graining or brush graining
• electrochemical graining which is also called electrolytic polishing
• chemical graining which is called chemical graining.
• problems with the mechanical graining process include scuff marks, stains and residue of an abrasive used.
• the electrochemical graining process makes it possible to change the depth of the graining as well as the form of grains by controlling the quantity of electricity. However, it requires a large quantity of electricity and a long time to create grains suited for printing plates which leads to high production costs.
• the chemical graining process grains aluminum or aluminum alloy by a chemical etching reaction using an acid or an alkali etchant, and, hence, it is simple and suited for continuously treating aluminum or aluminum alloy strips, and is particularly advantageous for industrially producing plates having been treated on both sides.
• the present invention relates to an aluminum alloy, a lithographic printing plate support and a litho- graphic printing plate using the aluminum alloy which solve the above-described problems.
• an object of the present invention is to provide an aluminum alloy, a lithographic printing plate support which is capable of forming uniformly and densely distributed pits thereon by an etching treatment with a small quantity of aluminum dissolution and obtaining a desired surface roughness, and a litographti printing plate using the same which is suited for printing.
• the present invention relates to:
• the aluminum alloy of the present invention shows a good solution velocity for chemical etching treatment and contains an intermetallic compound capable of accelerating formation of uniform pits.
• Etching treatment of the plate with a popularly used acid or alkali produces uniformly and densely distributed pits on the surface of the plate.
• an anode oxidation film is difficult to produce on impurities, and, hence, incorporation of too much impurities would cause film defects, resulting in the formation of background stain upon printing.
• Alloys containing Fe and, optionally, Cu and/or Mg show such a large solution velocity for both acids and alkalis that a proper solution can be selected depending upon the amount of etching desired and the desired pattern.
• the aluminum alloy of the present invention is produced by hot-rolling of a casting composition for aluminum alloy containing Al, Fe and at least one element selected from among Sn, In, Ga and Zn, and optionally Cu and/or Mg, at 400°C to 600°C, and intermedium-annealing at 300°C to 500°C followed by cold-rolling to obtain a desired thickness.
• Aluminum and other contents in the alloy thus-obtained were identified using fluorescence x-ray analysis and/or emission spectroanalysis.
• the printing plate support in accordance with the present invention is produced as follows.
• the support comprised of the alloy of the present invention is subjected to at least one chemical etching step and optionally followed by electrochemical etching step.
• the chemical etching of the aluminum alloy is carried out using an acid or alkali such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, etc., or a mixture of two or more of these acids, and sodium hydroxide, sodium carbonate, sodium tertiary phosphate, sodium silicate, etc., are used as the alkali.
• Concentration and temperature of the etching solution depend upon etching time and required surface roughness but, as a general guide, the concentration ranges from 1 to 50%, the temperature from 20°C to 90°C, and the treating time from 10 seconds to about 4 minutes. Both chemical etching by alkali and acid may be carried out in this order or in the reverse order.
• a degreasing treatment is conducted prior to the chemical etching.
• pickling is effected.
• Acids to be used for the pickling include nitric acid and sulfuric acid.
• the pickling reaction can be accelerated by adding hydrogen peroxide. sulfuric acid.
• the pickling reaction can be acceleratrd by adding hydrogen peroxide.
• the surface of the thus-treated aluminum plate must have uniformly and densely distributed pits having an average depth of 1 to 1 0 u , which corresponds to an average roughness of 0.3 to 1.2 ⁇ m (presented as Ra) and an opening diameter of 1 to 10 p.
• the average depth of pits is an important parameter in determining surface roughness and a uniform pit pattern is necessary for attaining printing durability and staining resistance required for printing plates. If the pit depth is less than 1 um, the surface roughness is limited to 0.2 ⁇ m (Ra) at the highest which fails to give high printing durability and enough water retention to the resulting printing plate. On the other hand, if the pit depth is more than 10 pm, the surface roughness exceeds 1.2 ⁇ m (Ra) and staining resistance tends to be deteriorated. In addition, it becomes substantially difficult to form a uniform etching pit pattern wherein the pits have a uniform diameter and a uniform depth, and the amount of etched aluminum is increased, resulting in an unpractically high etching cost.
• the base plate having an average roughness of 0.3 to 1.2 um (Ra) can itself be practically used as a lithographic printing plate by providing thereon an anodically oxidized film to strengthen corrosion resistance and abrasion resistance of the surface.
• the plate is further improved in view of printing durability, staining resistance, and tone reproducibility.
• a support for a lithographic printing plate having improved printing durability, staining resistance, and tone reproducibility can be produced by subjecting the above-described surface to an electrochemical etching treatment in an electrolytic solution containing hydrochloric acid or its salt, nitric acid or its salt, or a mixture thereof using DC or AC.
• Concentration of the acid or salt thereof in the electrolytic solution is preferably 0.1 to 100 g, more preferably 0.5 to 60 g, per liter of the electrolytic solution.
• the temperature of the electrolytic solution ranges preferably from 20°C to 60°C, and the treating time from 1 second to 10 minutes, preferably 3 seconds to 5 minutes.
• Conditions of electrochemical etching depend on required surface roughness and pit pattern of the support. Observation of the surface of the thus-obtained support under a scanning type electron microscope (SEM) revealed that secondary pits having an average opening diameter of 5 pm or less were uniformly and superimposedly distributed. In addition, a section of the support was prepared by using a microtome, and the profile of the section was surveyed under the scanning electron microscope to find that the average depth of the pits was 1 um or less. Samples having widely varying diameters and depths of pits can be prepared by properly selecting the kind of electrolytic bath, kind of source of electric power, and electrolysis conditions. The support thus-obtained by the electrochemical etching treatment has an average roughness of 0.3 to 1.2 ⁇ m (Ra) which is almost the same value as the support obtained by the chemical etching.
• Ra average roughness of 0.3 to 1.2 ⁇ m
• the inventors have found that the best balanced performance including printing durability, staining resistance, tone reproducibility, etc., can be obtained by forming the secondary pits having an opening diameter of 5 ⁇ m or less or a depth of 1 ⁇ m or less on the surface having the primary pits of 1 to 10 ⁇ m in depth. If the pits have an opening diameter of more than 5 ⁇ m or a depth of more than 1 ⁇ m, the primary pits are destroyed and suffer reduction of substantial pit depth, adversely affecting printing durability and water retention.
• Formation of the secondary pits by electrochemical etching can be effected by using an electrolytic bath of either hydrochloric acid or nitric acid.
• an electrolytic bath of either hydrochloric acid or nitric acid In order to render the pit diameter uniform, electric current of a special alternating wave described in U.S. Patent 4,087,341, compounds such as amines described in U.S. Patent 3,755,116, sulfuric acid described in Japanese Patent Application (OPI) No. 57902/74 (the term "OPI” as used herein refers to a "published unexamined Japanese patent application"), boric acid described in U.S. Patent 3,980,539, phosphoric acid shown in West German Patent Application (OLS) 2,250,275 and U.S.Patent 3,887,447, etc., may be employed or added.
• Stains remaining on the electrochemically etched surface can be removed by contacting the surface with 50 to 90°C, 15 to 65 wt% sulfuric acid as described in Japanese Patent Application (OPI) No. 12739/78 or by etching with an alkali described in Japanese Patent Publication No. 28123/73.
• the thus-treated aluminum alloy plate can be used as such as a support for a lithographic printing plate.
• an anode oxidation film may further be provided thereon to use as a high quality lithographic printing plate support.
• the thickness of the anode oxidation film is preferably 0.1 to 10 g/m , more preferably 0.1 to 5 g/ m 2 .
• the anodic oxidation processing can be carried out using techniques which have so far been employed in the art. Specifically, an anodically oxidized film can be form on the surfaces of aluminum support by passing DC or AC current to the aluminum support in an aqueous solution containing sulfuric acid, phosphoric acid, oxalic acid, or a mixture of two or more of these acids. Anodizing conditons are changed depending upon what kind of electrolytic solution is used and, therefore, they cannot be determined indiscriminately.
• an electrolytic solution having a concentration of 1 to 80 wt%, a solution temperature of 5 to 70°C, a current density of 0.5 to 60 ampere/dm , a voltage applied of 1 to 100 v and an electrolyzing time of 10 to 100 seconds can produce a preferable result.
• anodically oxidized film forming processes are the processes used in British Patent 1,412,768, wherein anodic oxidation is carried out in sulfuric acid by sending a high density electric current, and the process described in U.S. Patent 3,511,661 (incorporated herein by reference to disclose a process), wherein anodic oxidation is carried out using phosphoric acid as an electrolytic bath.
• the thickness of the anodically oxidized film is preferably 0.1 to 10 g/m 2 , more preferably 0.1 to 5 g/m2.
• the aluminum plate which has been anodically oxidized may be further treated with an aqueous solution of an alkali metal silicate such as sodium silicate or the like using a convtional technique, e.g., a dipping technique, as described in U.S. Patents 2,714,066 and 3,181,461 (incorporated herein by reference to disclose such techniques).
• a convtional technique e.g., a dipping technique
• a subbing layer made up of hydrophilic cellulose (e.g., carboxymethyl cellulose, etc.) containing a water-soluble metal salt (e.g., zinc acetate, etc.) and ranged in preferable thickness of 0.001 to 1 g/m 2 , more preferable thickness of 0.005 to 0.5 g/m 2 , may be additionally provided on the anodically oxidized aluminum plate, as described in U.S. Patent 3,860,426 (incorporated herein by reference to disclose how to provide a subbing layer).
• hydrophilic cellulose e.g., carboxymethyl cellulose, etc.
• a water-soluble metal salt e.g., zinc acetate, etc.
• a light-sensitive layer which is known to have been used for presentitized plates is provided to produce a light-sensitive lithographic printing plate.
• the lithographic printing plate obtained by subjecting this presensitized plate to a plate making process has excellent properties.
• Light-sensitive layer comprised of a diazo resin and a binder:
• Preferred examples of the diazo resin include those described in U.S. Patents 2,063,631, 2,667,415, Japanese Patent Publication Nos. 18001/74, 45322/74, 45323/74 and British Patents 1,312,925 and 1,023,589.
• Preferred examples of the binder include those described in British Patents 1,350,521 and 1,460,978, U.S. Patents 4,123,276, 3,751,257, and 3,660,097, and Japanese Patent Application (OPI) No. 98614/79 (the term "OPI” as used herein refers to a "published unexamined Japanese Patent Application").
• Light-sensitive layer comprised of an o-quinonediazide compound:
• o-quinonediazide compound examples include o-naphthoquinonediazide compounds as 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 and many other publications.
• Light-sensitive layer comprised of a composition containing an azide compound and a binder (macromolecular compound):
• compositions comprised of azide compounds and water-soluble or alkali-solution macromolecular compounds which are described in British Patents 1,235,281 and 1,495,861, Japanese Patent Application (OPI) Nos. 32331/76 and 36128/76, and so on, and compositions comprised of azido group-containing polymers and macromolecular compounds as binders, as described in Japanese Patent Application (OPI) Nos. 5102/75, 84302/75, 84303/75, and 12984/78.
• Light-sensitive layers comprised of other light-sensitive resinous compositions:
• polyester compounds disclosed in Japanese Patent Application (OPI) No. 96696/77 polyvinyl cinnamate series resins described in British Patents 1,112,277, 1,313,390, 1,341,004 and 1,377,747 and photopolymerizable photopolymer compositions described in U.S. Patents 4,072,528 and 4,072,527, and so on.
• the amount (thickness) of the light-sensitive layer to be provided on the support is controlled to about 0.1 to about 7 g/m 2 , preferably 0.5 to 4 g/m 2 .
• Lithographic printing plates after imagewise exposure, are subjected to processings including a developing step in a conventional manner to form resin images.
• a lithographic printing plate having the light-sensitive layer (1) constituted with a diazo resin and a binder has unexposed portions of the light-sensitive layer removed by development after imagewise exposure to produce a lithographic printing plate.
• a lithographic printing plate having a light-sensitive layer (20) has exposed portions of the light densitive layer which are removed by development with an alkaline aqueous solution after imagewise exposure to produce a lithographic printing plate.
• a casting composition containing 99.26% of Al, 0.70 of Fe and 0.04% of Sn was subjected to hot-rolling, which temperature was 500°C, and then to intermedium-annealing at 400°C followed by cold-rolling.
• the aluminum alloy plate thus-obtained had 0.30 mm of thickness.
• the alloy was confirmed to contain 99.26% of Al, 0.70% of Fe and 0.04% of Sn by a fluorescene X-ray analysis using X-ray.
• the following aluminum alloy plates were prepared and subjected to a chemical graining treatment for 1 minute at 60°C in 10% NaOH. Surface roughness of the thus-treated plates was measured, and the pit pattern was observed under a scanning electron microscope (SEM).
• Samples were numbered to combine an alloy number with an etching process employed, for example, alloy No. 1 treated by etching process of Example 2 was called Sample No. 1A.
• Sample Nos. 9A to 13A containing Fe and Mg as a main component have pit patterns having 2 to 8 ⁇ of opening diameter and 0.45 ⁇ m or more of average surface roughness.
• Sample Nos. 1A to 8A which contain Cu but contain no Mg have uniform pit patterns having 2 to 8 ⁇ of pit diameter. Those samples have a considerably good surface-appearance in comparison with Comparative Samples. Values of average surface roughness is slightly low in comparison with Samples containing Mg.
• Sample Nos. 1'A, 2'A and 3'A and Sample Nos. 1 to 4A and 6A to 13A were subjected to an electrochemical etching treatment in a 7 g/liter nitric acid aqueous solution in an electricity amount of 100 coulomb/dm 2 using a special alternating wave current described in Japanese Patent Application (OPI) No. 67507/78, then subjected to desmutting treatment of dipping in a 30% H 2 SO 4 aqueous solution at 55°C for I minute.
• OPI Japanese Patent Application
• Sample Nos. 1B to 13B and Sample Nos. 1'B to 3'B had secondary pits of 0.1 to 0.8 ⁇ m of depth and 1 to 3 ⁇ m of opening diameter.
• the surface roughness was the same as that of samples treated by alkali etching process shown in Table 1.
• Example 1 On the supports base comprising Sample Nos. 7A, 7B, 10A and 10B and Comparative Sample No. 3'B obtained in Example 1 was coated the following light-sensitive layer in a dry thickness of 2.0 g/ m 2 .
• the thus obtained light sensitive lithographic printing plates were each imagewise exposed for 70 seconds by means of a metal halide lamp of 3 kw placed at a distance of 1 meter, and dipped in the following developing solution for 1 minute at room temperature. Then, the surface of each plate was lightly rubbed by an absorbent wadding to remove unexposed areas, thus lithographic printing plates were obtained, respectively.
• the plates of Nos. 10A and 10B are superior in printing durability to those of Nos. 7A and 10A.
• Sample No. 1 and comparative sample Nos. 2' and 3', shown in Example 1 were subjected to a first chemical graining treatment in 10% sodium hydroxide at 60°C for 1 to 5 minutes, then to a second chemical graining treatment in an aqueous mixture solution of 300 ml/liter nitric acid and 150 m./liter sulfuric acid at 90°C for 3 minutes, followed by observation under SEM and measurement of surface roughness.
• sample Nos. IC 1 to IC 5 A plane with a large surface roughness was formed on sample Nos. IC 1 to IC 5 due to its large solution quantity for both acid and alkalishin assition sample Nos. IC 1 to IC 5 had a mailti pit pattern wherein uniform 1 to 5 ⁇ pits were formed with acid in uniform 2 ⁇ to 8- ⁇ -pits having been formed with alkali.
• Sample No.1A described in Example 2 comparative sample Nos. 2'p and 3'A and sample No. IC 5 having been subjected to two-stage graining treatments in Example 4 were anodized in an electrolytic solution containing 20% sulfuric acid as a major component at a bath temperature of 30°C to provide thereon a 3 g/m 2 oxide film, then dipped in a 2.5% aqueous solution of sodium silicate (JIS No.3) at 60°C for 1 minute, washed throughly with water, and dried.
• JIS No.3 sodium silicate
• sample No. 1A The thus-treated samples prepared from sample No. 1A, comparative samples Nos.2'A and 3'A,and sample No. IC 5 were referred to as sample Nos. (lA), (2'A), (3'A) and (IC 5 )D, respectively.
• sample Nos. (lA), (2'A), (3'A) and (IC 5 )D On each of the thus-prepared samples was coated the solution used in Example 3 in a dry thickness of 2.0 g/m 2 to prepare lithographic printing plates.
• the thus-obtained light-sensitive lithographic printing plates were each imagewise exposed for 70 seconds by means of a metal halide lamp of 3 kw placed at a distance of I meter and dipped in the following deveioping solution for one minute at room temperature. Then, the surface of each plate was lightly rubbed by an absorbent wadding, to remove unexposed areas, thus printing plate Nos. (1A), (2'A), (3'A)and (IC 5 )D were obtained, respectively.
• Sample Nos. 9A and 8A, and Comparative sample No. 1'A, shown in Example 2 were anodized in an electrolytic solution containing 20% sulfuric acid as a major component at a bath temperature of 30°C to provide thereon a 3 g/m 2 oxide film, then dipped in a 2.5% aqueous solution of sodium silicate (JIS No.3) at 60°C for 1 minute, washed throughly with water and dried.
• JIS No.3 sodium silicate
• the lithographic printing platesthus obtained were each imagewise exposed for 70 seconds by means of a metal halide lamp of 3 KW placed at a distance of 1 meter, and dipped in the developing solution shown in Example 3 for 1 minute at room temperature. Then, the surface of each plate was lightly rubbed by an adsorbent wadding, to remove unexposed areas, thus printing platesNos. (9A)E, (8A)E and (l'A)E were obtained, respectively.
• Sample Nos. (9A)E and (8A)E are superior to Sample No. (l'A)E in printing durability and staining resistance, and further Sample No. (9A)E is excellent in comprarison with Sample Nos. (8A)E and (1'A)E due to a larger average surface roughness of Sample No. (9A)E.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Printing Plates And Materials Therefor (AREA)

Applications Claiming Priority (4)

Publications (3)

Family

ID=26433561

Family Applications (1)

Country Status (2)

Cited By (8)

Families Citing this family (1)

Citations (8)

• 1983
  • 1983-05-31 EP EP83105393A patent/EP0096347B1/de not_active Expired
  • 1983-05-31 DE DE8383105393T patent/DE3378063D1/de not_active Expired
  • 1983-05-31 DE DE1983105393 patent/DE96347T1/de active Pending

Patent Citations (8)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events