Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2001-03-20
2003-02-11
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S191000, C430S192000, C430S193000, C430S190000, C430S302000, C430S166000
Reexamination Certificate
active
06517987
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a positive-working presensitized plate useful for preparing a lithographic printing plate comprising a positive-working photosensitive composition coated on a substrate, which the composition comprises a positive-working photosensitive compound and a specific polymer.
A photosensitive composition comprising o-naphthoquinonediazide compound and a novolak-type phenol resin has been industrially utilized for the preparation of lithographic printing plate or photoresist as a useful photosensitive composition.
However, the novolak-type phenol resin mainly used for the photosensitive composition has many defects, for example, poor adhesion to the substrate, brittleness of the film made of the resin, poor application property, poor abrasiveness, insufficient durability during printing and poor chemical-resistant. Particularly when it is used with UV ink, the durability becomes insufficient.
In order to improve these properties, the presensitized plate is generally subjected to burning treatment (that is, to heat the plate after light exposure and development). However, such burning treatment causes another problem. That is, it causes contamination on prints because low molecular compounds are sublimated from photosensitive layer of an image area to adhere to a non-image area.
To solve the problem, a number of polymers are studied as a binder for the photosensitive composition. For example, it has been proposed to use the following compounds as a binder; polyhydroxystyrene or hydroxystyrene copolymer described in Japanese Patent Publication for Opposition Purpose (hereunder referred to as “J.P. KOKOKU”) No. Sho 52-41050, or a polymer comprising a structural unit derived from acrylic acid as described in Japanese Patent Unexamined Publication (hereunder referred to as “J.P. KOKAI”) No. Sho 51-34711. In addition, it has been proposed to use the following compounds as a binder; a polymer comprising a sulfonamide group as described in J.P. KOKAI No. Hei 2-866, polymers comprising a group derived from acrylic acid with phenolic hydroxy group as described in J.P. KOKAI Nos. Sho 63-89864, Hei 1-35436, Hei 1-52139, and Hei 8-339082. However, lithographic printing plates using such polymers often show narrow development latitude.
In addition, when the positive-working presensitized plate useful for preparing a lithographic printing plate having o-naphthoquinonediazide compound as a photosensitive compound is developed with an alkaline developer containing water as a main solvent, sometimes red-colored material is formed at halftone of image area. This phenomenon is a result of a coupling reaction between decomposed material of o-naphthoquinonediazide and unreacted compound. If the red-corolred material remains on the substrate, it is difficult to delete the image area, i.e., the workability to remove insoluble image becomes deteriorated.
In addition, when multiple images are formed (that is, when images are formed using plural imaging films) on a presensitized plate for lithographic printing plate at various positions, the position of each film is marked on the photosensitive layer to register the positions of the films using an oil-base ball-point pen. Solvent used in ink for the ball-point pen sometimes erodes and resolves the photosensitive layer. Especially when the mark is present on image area, the marked portion on the photosensitive layer will be removed after development and thus, the mark would be printed out. Therefore, there is a need for a photosenstive composition having a resistance to erosion by ink of ball-point pen (hereinafter, this property will be referred to as “adaptability to ball-point pen”).
Generally, a lithographic printing plate is prepared by exposing a presensitized plate having a photosensitive layer on which image film is overlapped and by developing thus exposed plate. In such preparation process for the lithographic printing plate, time between the exposure and the development is not constant. Sometimes, the development is conducted several days after the exposure. The sensitivity of the plate varies with time after the exposure. Therefore, sometimes it causes a problem that a normal printing material can not be obtained.
In addition, many of these photosensitive materials have defaults such as short lifetime and low sensitivity to active lights. Thus, these compounds do not show sufficient properties.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a positive-working presensitized plate useful for preparing a lithographic printing plate which shows wide latitude in development, good printing durability, chemical-resistant, coupling property, adaptability to ball-point pen, sensitivity, shelf stability, as well as small change of sensitivity with time after exposure.
The inventors of the present invention found that the above-described problems can be solved by the positive-working presensitized plate useful for preparing a lithographic plate comprising a positive-working photosensitive composition coated on a substrate, which the composition comprises (a) at least one ester of 1,2-naphthoquinone-2-diazide-5-sulfonic acid, (b) at least one ester of 1,2-naphthoquinone-2-diazide-4-sulfonic acid, and (c) at least one polymer that is insoluble in water and soluble in an aqueous alkaline solution and that comprises at least one sulfonamide group, or by the positive-working presensitized plate useful for preparing a lithographic printing plate comprising a positive-working photosensitive composition coated on a substrate, which the composition comprises (a) at least one ester of 1,2-naphthoquinone-2-diazide-5-sulfonic acid, (b) at least one ester of 1,2-naphthoquinone-2-diazide-4-sulfonic acid, and (c) at least one polymer which is insoluble in water and soluble in an aqueous alkaline solution and which comprises at least one urea bond or urethane bond, to thus complete the present invention.
Namely, the positiive-working presensitized plate useful for preparing a lithographic printing plate comprising a positive-working photosensitive composition comprising at least one ester of 1,2-naphthoquinone-2-diazide-5-sulfonic acid, at least one ester of 1,2-naphthoquinone-2-diazide-4-sulfonic acid, and at least one polymer which is insoluble in water and soluble in an aqueous alkaline solution and which comprises at least one group or bond selected from sulfonamide group, urea bond or urethane bond, would result in improvement of chemical-resistance and printing durability, and good sensitivity, coupling property, adaptability to ball-point pen, shelf stability, and stability of sensitivity with time after exposure.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The details of the present inveniton will be described below. The positive-working presensitized plate for making a lithographic printing plate of the present invention can be prepared by applying on a substrate that has been subjected to hydrophilization treatment, a photosensitive layer comprised of positive-working photosensitive composition comprising (a) at least one ester of 1,2-naphthoquinone-2-diazide-5-sulfonic acid, (b) at least one ester of 1,2-naphthoquinone-2-diazide-4-sulfonic acid and (c) at least one polymer that is insoluble in water and soluble in an aqueous alkaline solution and that comprises at least one group or bond selected from the group consisting of sulfonamide group, urea bond and urethane bond.
(Photosensitive Compound)
Ester of 1,2-naphthoquinone-2-diazide-5-sulfonic acid, and ester of 1,2-naphthoquinone-2-diazide-4-sulfonic acid
Examples of the esters of 1,2-naphthoquinone-2-diazide-5-sulfonic acid and ester of 1,2-naphthoquinone-2-diazide-4-sulfonic acid include a variety of known compounds comprising 1,2-naphthoquinonediazide group. Especially preferred compounds are esters of a variety of hydroxy compounds and 1,2-naphthoquinonediazidesulfonic acids. Examples of such hydroxy compound include phenols such as phenol, resorcin, cresol, pyrogallol, and condensation product thereof with a carbonyl group-c
Fujita Kazuo
Nagashima Akira
Tan Shiro
Burns Doane , Swecker, Mathis LLP
Chu John S.
Fuji Photo Film Co. , Ltd.
LandOfFree
Positive-working presensitized plate useful for preparing a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Positive-working presensitized plate useful for preparing a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Positive-working presensitized plate useful for preparing a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3169432