Metal treatment – Stock – Aluminum base
Reexamination Certificate
2001-02-07
2003-06-03
Wyszomierski, George (Department: 1742)
Metal treatment
Stock
Aluminum base
C420S548000, C420S550000
Reexamination Certificate
active
06572715
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an aluminum alloy support body for a presensitized plate used in lithographic printing and, more particularly, to an aluminum alloy support body for a presensitized plate, which is superior in the uniformity of the grained surface due to electrochemical etching. The present invention also relates to a method of producing the same.
BACKGROUND OF THE INVENTION
Lithographic printing is performed by subjecting a presensitized plate comprising a support body made of an aluminum alloy and a photosensitive material containing a diazo compound that serves as a photosensitive substance to a plate-making treatment such as image exposure or development to form an imaged portion, winding the plate around a cylindrical plate drum of a press, adhering ink onto the imaged portion in the presence of wet water adhered onto the non-imaged portion, transferring ink to a rubber blanket, and printing on the surface of a paper.
As the support body for the presensitized plate, an aluminum alloy plate subjected to a surface treatment such as graining treatment due to electrochemical etching or anodizing oxidation treatment is generally used. As the aluminum alloy used for this purpose, JIS1050(AA1050) alloy (pure aluminum having purity of 99.5% or higher), JIS1100(AA1100) alloy (Al-0.05~0.20% Cu alloy) and JIS3003(AA3003) alloy (Al-0.05~0.20% Cu-1.5% Mn alloy) were exclusively used at first.
Such an aluminum alloy support body for the presensitized plate requires various properties such as:
(1) uniform grained surface due to electrochemical etching,
(2) good adhesion of photosensitive material, and
(3) no strain of the imaged portion during the printing.
However, since JIS1050(AA1050), JIS1100(AA1100) and JIS3003(AA3003) alloys themselves cannot sufficiently satisfy the respective requirements described above, various improvements have been made.
For example, Japanese Patent Application, First Publication No. Sho 58-221254 discloses an offset printing plate consisting essentially of 0.02 to 0.15% of Si; 0.1 to 1.0% of Fe; not more than 0.003% of Cu; and the balance of Al and unavoidable impurities.
Also Japanese Patent Application, First Publication No. Sho 62-148295 discloses a lithographic printing aluminum alloy support body consisting essentially of 0.05 to 1.0% of Fe; not more than 0.2% of Si; not more than 0.05% of Cu; and the balance of Al and unavoidable impurities, the content of a simple substance Si distributed in a constitution being not more than 0.012%.
The invention described in Japanese Patent Application, First Publication No. Sho 58-221254 suggests controlling the Cu content to within 0.003% or less because the corrosion resistance is lowered with the increase of the Cu content, thereby increasing contamination of the non-imaged portion during the printing. The technique described in Japanese Patent Application, First Publication No. Sho 62-148295 has an effect such that a grained surface due to electrochemical etching is obtained and streaking (strip-shaped unevenness) does not occur and, moreover, contamination of the non-image portion can be inhibited during the printing.
Therefore, it has become difficult for conventional aluminum alloy support bodies described in Japanese Patent Application, First Publication No. Sho 58-221254 and Japanese Patent Application, First Publication No. Sho 62-148295 to sufficiently cope with the requirement of an improvement in printing accuracy (or print contrast ratio). Particularly, it has become necessary to further improve the uniformity of the grained surface due to electrochemical etching. Moreover, forming an excellent grained surface having excellent uniformity by an electrochemical graining treatment within a short time for the purpose of reducing the cost has become an important requirement.
To cope with these requirements, Japanese Patent Application, First Publication No. Hei 9-184039 suggests an aluminum alloy support body for a presensitized plate with a composition consisting essentially of 0.25 to 0.6% by weight of Fe; 0.03 to 0.15% by weight of Si; 0.005 to 0.05% by weight Ti; 0.005 to 0.20% by weight Ni; and the balance of Al and unavoidable impurities, the composition satisfying the relationship: 0.1≦Ni/Si≦3.7.
The aluminum alloy support body for a presensitized plate described in Japanese Patent Application, First Publication No. Hei 9-184039 makes it possible to improve the uniformity of the grained surface and to inhibit formation of pits due to dipping in an electrolytic solution in a non-electrically conducted state before an electrolytic treatment by inhibiting the chemical solubility, which is improved by adding Ni, due to the performance of inhibiting the chemical solubility of Si.
Also Japanese Patent Application, First Publication No. Hei 9-272937 suggests an aluminum alloy support body for a presensitized plate consisting essentially of 0.20 to 0.6% by weight of Fe; 0.03 to 0.15% by weight of Si; 0.006 to 0.05% by weight Ti; and 0.005 to 0.20% by weight Ni; the aluminum alloy support body further containing 0.005 to 0.050% by weight of one or more elements selected from the group consisting of Cu and Zn; 0.001 to 0.020% by weight of one or more elements selected from the group consisting of In, Sn and Pb; and the balance of Al and unavoidable impurities.
In the aluminum alloy support body for a presensitized plate described in Japanese Patent Application, First Publication No. Hei 9-272937, a difference in potential between an aluminum matrix and an intermetallic compound is controlled by incorporating one or more elements of Cu and Zn and one or more elements of In, Sn and Pb into the aluminum matrix in a solid state, thereby making the electrolytically grained surface uniform.
Although the uniformity of the grained surface was improved as compared with the prior art by the suggestions of Japanese Patent Application, First Publication No. Hei 9-184039 and Japanese Patent Application, First Publication No. Hei 9-272937, higher printing accuracy is required and still more uniformity of the grained surface is required at present. Thus, an object of the present invention is to provide an aluminum alloy support body for a presensitized plate in which the uniformity of the grained surface due to electrochemical etching is further improved, and a method of producing the same.
SUMMARY OF THE INVENTION
To solve the problems described above, the present inventors have studied about the uniformity of electrochemical etching of the aluminum alloy support body for a presensitized plate and found the following facts.
(1) An Al—Fe type intermetallic compound, which is crystallized or deposited in an aluminum matrix, acts as a cathode point during the electrochemical etching, thus controlling the solubility of an aluminum alloy support body for a presensitized plate.
(2) When Ni is added, Ni is incorporated into an Al—Fe type intermetallic compound to form an Al—Fe—Ni type intermetallic compound, thus making it possible to improve uniform solubility of an aluminum alloy support body for a presensitized plate.
(3) When rare earth elements are added, said rare earth elements are incorporated into the Al—Fe type intermetallic compound or Al—Fe—Ni type intermetallic compound described above to form crystals/deposits of an Al—Fe—X type or Al—Fe—Ni—X type (wherein X is one or more rare earth elements) intermetallic compound. Since these intermetallic compounds have properties capable of easily producing an electric current as compared with the Al—Fe type or Al—Fe—Ni type intermetallic compound, that is, X-free intermetallic compound, uniform solubility of an aluminum alloy support body for a presensitized plate can be improved by further improving the cathode reactivity during the electrochemical etching.
(4) Zn weakens an oxide layer to be formed on the surface of aluminum, thus improving the uniformity of the grained surface. Provided that excess Zn is added, the effect of weakening the oxide layer becomes too large and the dissolution amount becomes too large during the elec
Ishida Mitsuo
Komine Hirotaka
Yamaguchi Keitarou
Combs Morillo Janelle
Faegre & Benson LLP
Kodak Polychrom Graphics, LLC
Wyszomierski George
LandOfFree
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