Lithographic printing plate

Details Lithographic printing plate Lithographic printing plate

1996-12-10

2000-07-25

Codd, Bernard

Radiation imagery chemistry: process, composition, or product th

Imaged product

Including resin or synthetic polymer

4302711, 430302, 101457, 101461, 101462, 101465, G03F 7004

Patent

active

06093509&

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a Lithographic printing plate, particularly a lithographic printing plate which can be produced from a new photosensitive lithographic original plate simple in development treatment, highly repellent against ink even without being etched, and allowing the use of pure water as dampening water.


BACKGROUND ART

In lithographic printing, an image area capable of receiving ink and a non-image area capable of repelling ink respectively exist basically almost on the same level on a printing plate, and the difference between both the areas in ink acceptability is used so that the image area only may have ink deposited and subsequently transferred onto a material to be printed, such as paper. The lithographic printing plate usually uses a pre-sensitized plate.
The term "pre-sensitized plate" in this specification means the following.
As described in Teruhiko Yonezawa, "Introduction to Pre-Sensitized Plates (in Japanese)", K.K. Insatsu Gakkai Shuppanbu, Pages 18 through 81, an aluminum substrate treated to be hydrophilic is coated with a lipophilic photosensitive resin layer, and a photo lithographic technique is used to cause the photosensitive layer to leave on the image area and to expose the aluminum substrate surface on the non-image area, for having a dampening water layer formed on the surface to repel ink, for image formation. This plate is called a water-using pre-sensitized plate. There is also a waterless pre-sensitized plate, in which a silicone rubber layer is used as an ink repelling layer instead of the dampening water layer.
The waterless plate means a printing plate, the non-image area of which is made of a material capable of repelling the oil ink usually used for lithographic printing, such as silicone rubber or fluorine-containing compound, for image formation in combination with the image area capable of having ink deposited, to allow printing without using dampening water.
The former water-using pre-sensitized plate is in practice an excellent printing plate, and usually aluminum is used for the substrate. The surface of the aluminum substrate must be able to hold water, and be excellent in adhesiveness to the lipophilic photosensitive resin layer lest the photosensitive layer should peel and come off during printing from the surface. So, the aluminum surface is usually grained, and furthermore, as required, the grained surface is treated by anodized oxidation, etc., to improve the water-holding capacity and the adhesiveness to the photosensitive resin layer. Moreover, to secure the storage stability of the photosensitive resin layer, the aluminum surface is generally chemically treated by zirconium fluoride or sodium silicate, etc.
As can be seen from the above, the process for producing a water-using pre-sensitized plate is complicated and should to be simplified, and yet water-using pre-sensitized plates are widely used since they are excellent in printing capabilities such as printing durability and image reproducibility.
To solve the above problem, new lithographic materials equivalent or superior to the aluminum substrate in printing capabilities, but lower in material cost and simpler to produce are proposed as substitutes for the aluminum substrate. For example, Japanese Patent Publication (Kokoku) No. 56-2938 proposes to use a substrate coated with an ink repelling layer composed of a hydrophilic high polymer, instead of the aluminum substrate, and to form a photosensitive layer on the substrate. However, since a water resistant layer composed of an aldehyde condensation product of polyvinyl chloride, polyurethane or polyvinyl alcohol is simply covered with a hydrophilic layer composed of urea resin, the hydrophilic layer is insufficient in ink repellency, and in addition, poor in adhesion to the photosensitive resin layer, resulting in its being insufficient in printing durability. Furthermore, Japanese Patent Laid-Open (Kokai) No. 57-179852 proposes to coat a substrate with a hydrophilic radical-polymerized compound, and to irradiat

REFERENCES:
patent: 2800077 (1957-07-01), Marron
patent: 3476937 (1969-11-01), Vrancken
patent: 3793025 (1974-02-01), Vraneken et al.
patent: 5571658 (1996-11-01), Sonokawa et al.
Patent Abstracts of Japan, vol. 096, No. 003, Mar. 29, 1996, and JP 07 301920 A (Toyobo Co., Ltd.) Nov. 14, 1995, abstract only.
Patent Abstracts of Japan, vol. 018, No. 581, (P-1822), Nov. 7, 1994 and JP 06 214389 A, (Asahi Chem. Ind. Co. Ltd.), Aug. 5, 1994, abstract only.
Patent Abstracts of Japan, vol. 007, No. 250, (M-254), Nov. 8, 1983 and JP 58 134795 A, (Ricoh KK), Aug. 11, 1983, abstract only.

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