Radiation imagery chemistry: process – composition – or product th – Transfer procedure between image and image layer – image... – Diffusion transfer process – element – or identified image...
Reexamination Certificate
2001-04-02
2003-04-01
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Transfer procedure between image and image layer, image...
Diffusion transfer process, element, or identified image...
C430S230000, C430S510000, C430S517000, C430S519000, C430S522000, C430S570000, C430S583000, C430S591000, C430S595000, C430S606000
Reexamination Certificate
active
06541176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for making a lithographic printing plate, more specifically to a process for making a lithographic printing plate utilizing a silver complex diffusion transfer process and using-a scanning type exposure device on which a violet laser diode is mounted (which is generally called to as “an image setter” or “a plate setter”).
2. Prior Art
A lithographic printing plate using a silver complex diffusion transfer process (the DTR method) has already been known. On of which is a lithographic printing plate having a silver halide emulsion layer and a physical development nuclei layer on a support (for example, paper coated by a polyethylene resin, a polyethylene terephthalate film, etc.) in which order (hereinafter referred to as “a flexible lithographic printing plate”). Such a plate has been disclosed in, for example, U.S. Pat. Nos. 3,721,559, 3,490,905, 3,385,701, 3,814,603, 3,454,398, 3,764,323 and 3,099,209; Japanese Patent Publications No. 27242/1969 and No. 30562/1973; and Japanese Provisional Patent Publications No. 9603/1978, No. 21602/1978, No. 103104/1979 and No. 9750/1981.
The above-mentioned lithographic printing plate has a physical development nuclei layer on the surface of a silver halide emulsion layer in which gelatin is used as a binder, and silver halide crystals in the exposed silver halide emulsion layer causes chemical development by the DTR development to become black silver, and a non-image portion which is hydrophilic and mainly comprises a gelatin is formed. On the other hand, unexposed silver halide crystal becomes a silver complex by a silver complexing agent in a developing solution and diffuses to the physical development nuclei layer at the surface, and causes physical development in the presence of a nuclei to form an image portion mainly comprising a physical development silver which is ink-receptive.
Another type is a lithographic printing plate in which a silver halide emulsion layer is provided on a physical development nuclei carried on a roughened and anodized aluminum support (hereinafter referred to as “an aluminum lithographic printing plate”). This is described, for example, in Japanese Provisional Patent Publications No. 118244/1982, No. 158844/1982, No. 260491/1988, No. 116151/1991, No. 282295/1992, No. 216236/1993 and No. 81194/1994; and U.S. Pat. Nos. 4,567,131 and 5,427,889. In this lithographic printing plate, after developing treatment, the silver halide emulsion layer is subjected to wash off (removal by washing) after developing treatment, to appear an image portion comprising a metal silver membrane and a non-image portion comprising an aluminum anodized surface.
The above-mentioned two types of the lithographic printing plates are different in layer constitution, but they are common in forming an image silver by utilizing a silver complex diffusion transfer process. These lithographic printing plates are constituted by an image portion which accepts an oleophilic ink and a non-image portion which is hydrophilic and accepts water. Thus, in a usual lithographic printing, both of water (dampening solution) and ink are supplied on the lithographic plate, and the image portion accepts a coloring ink, and the non-image portion selectively accepts water, and printing is carried out by transferring the ink on the image portion to a paper for printing.
Also, in the lithographic printing plates utilizing the silver complex diffusion transfer process as mentioned above, it has been known a camera exposure type and a scanning exposure type. As the scanning exposure type lithographic printing plate, there are disclosed, for example, in U.S. Pat. Nos. 4,621,041 and 4,501,811; and Japanese Provisional Patent Publications No. 71055/1984, No. 71056/1984, No. 61752/1985, No. 75838/1985, No. 100148/1985, No. 179744/1985, No. 197737/1987, No. 197738/1987, No. 47756/1988, No. 68963/1988, No. 252863/1988, No. 13539/1989, No. 74241/1990, No. 251853/1990, No. 281708/1997, etc. As a light source for scanning exposure, it has generally been known a helium-neon laser, an argon laser, a semiconductor laser, a radiation diode, etc. The so-called CTP (computer to plate) system in which plate making is carried out by using these lithographic printing plates for scanning type exposure and a laser exposure machine (which is called to as “an image setter” or “a plate setter”) to directly printing a digital image to a printing plate has rapidly spread in recent years.
However, handling of the plate making operation of the lithographic printing plate for the scanning type exposure as mentioned above must be carried out in a dark room so that there are problems in workability and safety. Accordingly, it has earnestly been desired to develop a CTP system which can handle in a bright room or under light safe light (under yellow fluorescent light).
In extremely recent years, a scanning type exposure device on which a violet laser diode having an oscillation wavelength at 400 to 430 nm is mounted has been developed and used. This exposure device has a shorter wavelength of a light source than the conventional exposure device as mentioned above so that it has merits that it is excellent in fine line reproducibility and has a rapid output rate. However, a lithographic printing plate having a practically usable sensitivity capable of sufficiently effecting printing and having an excellent printing endurance as a printing plate has not yet been developed. Moreover, it has earnestly been desired to develop a lithographic printing plate having a practically usable sensitivity and is capable of handing under a light room.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method of making a lithographic printing plate using a lithographic printing plate material utilizing the silver complex diffusion transfer process which is capable of handing under light room conditions, i.e., under bright safe light (yellow fluorescent light) and a scanning type exposure device on which a violet laser diode is mounted. Another object of the present invention is to provide a lithographic printing plate material for a violet laser scanning exposure excellent in printing endurance.
The above-mentioned objects of the present invention has been accomplished basically by a process for making a lithographic printing plate.
(1) A process for making a lithographic printing plate, which comprises subjecting a lithographic printing material having at least a silver halide emulsion layer and a physical development nuclei layer on a support and having a sensitivity at a wavelength of 400 nm to 440 nm of 20 &mgr;J/cm
2
or less, and having substantially no sensitivity at a wavelength of 450 nm or longer to scanning exposure by a scanning type exposure device on which a violet laser diode is mounted, and then subjecting to developing treatment.
(2) A process for making a lithographic printing plate, which comprises subjecting a lithographic printing material having at least a silver halide emulsion layer containing at least one of sensitizing dyes represented by the following formulae (I), (II) and (III):
wherein Z
1
represents a group of atoms necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring, Q1 represents O, S, NR
11
or CO—NR
12
, and Q
2
represents O, S or NR
13
, where R
11
, R
12
and R
13
may be the same or different from each other and each represents a hydrogen atom, an alkyl group, or an aryl group, and M1 represents a counter ion for neutralizing an electric charge of the molecule,
wherein Z
2
and Z
3
each represents a group of atoms necessary for forming a 5- or 6-membered nitrogen-containing heterocyclic ring, provided that both of Z
2
and Z
3
do not contain a sulfur atom simultaneously, R
1
and R
2
may be the same or different from each other and each represents an alkyl group, L
1
represents a methyne group, and M
2
represents a counter ion for neutralizing an electric charge of the molecule,
wherein Z
4
represents a group
Miyazaki Takashi
Shimonodan Satoshi
Tanaka Etsuji
Yamano Motozo
Manelli Denison & Selter PLLC
Mitsubishi Paper Mills Ltd.
Schilling Richard L.
White, Jr. Paul E.
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