Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2002-01-16
2003-07-15
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S271100, C430S302000, C430S348000, C430S944000, C430S945000, C101S453000, C101S465000
Reexamination Certificate
active
06593059
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a negative or positive planographic printing plate precursor. Precisely, the invention relates to such a planographic printing plate precursor capable of being processed into a printing plate through scanning exposure based on digital signals. It has high sensitivity and a long press life thus providing good prints with no stain, and it can be directly set in a printer to give prints, and does not require any special development after image formation thereon.
2. Description of the Related Art
Much research is being done on printing plates for computer-to-plate systems which have made remarkable progress in recent years. For further process rationalization and solving the problem of waste treatment, for example, “development-less” planographic printing plate precursors capable of being directly set in printers and which do not require development after image formation thereon are being studied, and various methods for preparing them have been proposed.
A technique of in-printer development is known as one method of simplifying plate-making operations. This comprises putting an exposed printing plate precursor onto a cylinder of a printer and then applying dampening water and ink thereto while the cylinder is rotated to thereby remove the non-image area of the precursor. Specifically, in this method, a printing plate precursor is, after being exposed for image formation thereon, directly set in a printer, and processed in an ordinary printing manner to give prints. The planographic printing plate precursor applicable to the development system must satisfy two requirements; one is that its non-image area should be capable of being readily and completely removed through treatment with a hydrophilic component such as dampening water such that no residue is left therein, and the other is that the recording layer in its image area should not peel easily and should have good adhesiveness to the underlying support. After the recording layer has been removed from the non-image area of the processed plate through the treatment, the hydrophilic support face is exposed outside. One problem with this is that, if the exposed support face is not sufficiently hydrophilic, ink will adhere thereto and cause stains on the printed matter.
We, the present inventors previously filed a Japanese patent application No. 2000-119587 which relates to a planographic printing plate precursor that satisfies the two requirements. The planographic printing plate precursor of that invention is processable in printers, and it comprises a hydrophilic layer which contains a hydrophilic graft polymer, and a thermosensitive polymer layer whose polymer undergoes, hydrophilicity/hydrophobicity conversion when excited by some external force, for example, by application of energy thereto. The planographic printing plate precursor is processable in printers and gives high-quality images which have no stain. However, there is still room for further improvement with respect to the adhesiveness between the hydrophilic layer and the thermosensitive layer therein.
SUMMARY OF THE INVENTION
With the drawbacks of the prior art techniques described above taken into consideration, the object of the invention is to provide a planographic printing plate precursor having the advantages of good processability in printers, high sensitivity and long press life.
The polymer included in the planographic printing plate original form which we have previously proposed includes a polymer capable of undergoing a hydrophilicity/hydrophobicity conversion when same external force is applied thereto. Through our studies, we have found that when the polymer is modified by introducing thereinto a functional group capable of interacting with the graft polymer existing on the surface of the support of the precursor, then the adhesiveness between the constitutive layers can be improved to ensure satisfactory press life of the printing plate. On the basis of this finding, we have achieved the present invention.
Specifically, the planographic printing plate precursor of the invention has, on a support having a hydrophilic surface with hydrophilic graft polymer chains existing therein, a thermosensitive layer containing a polymer having, in the molecule, a functional group capable of interacting with the hydrophilic graft polymer and a functional group that undergoes hydrophilicity/hydrophobicity conversion through exposure to heat, acid or radiation.
The planographic printing plate precursor of the invention has a hydrophilic surface of a graft polymer on an aluminium substrate, and therefore has good hydrophilicity and heat insulation owing to the hydrophilic graft polymer existing on the support. Heat applied to the precursor is effectively prevented from being diffused into the aluminium support, and high-sensitivity image recording on the precursor is ensured. Due to having high hydrophilicity, the hydrophilic graft polymer on the support ensures good image formation on the processed plate with no staining in the non-image area thereof. In addition, since the recording layer of the planographic printing plate precursor of the invention contains a polymer compound having a functional group capable of forming strong bonds with the graft polymer component existing on the surface of the support, the adhesiveness between the support surface and the thermosensitive layer is greatly improved, and the press life of the plate is much enhanced.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is described in detail hereinunder.
The planographic printing plate precursor of the invention has, on a support having a specific hydrophilic surface, a thermosensitive layer containing a polymer capable of interacting with the polymer that constitutes the hydrophilic surface of the support.
(A) Support Having a hydrophilic Surface with Hydrophilic Graft polymer Chains Existing Therein
First described is the hydrophilic surface of the support.
A hydrophilic surface of the support is meant to indicate the existence of hydrophilic graft polymer chains on the surface of the support. Concretely, hydrophilic graft polymer chains may bond directly to the surface of the support; or a stem polymer compound having hydrophilic graft polymer chains in its side branches may be used in such a manner that the polymer compound thus having hydrophilic graft polymer chains in its side branches is bonded to the surface of the support or is disposed in the support surface through coating or coating followed by crosslinking. In the invention, the cases in which such hydrophilic graft polymer chains are directly bonded to the surface of the support is referred to as “surface graft”; and when they are introduced into the cross-linked polymer film structure, it is referred to as “cross-linked hydrophilic layer having hydrophilic graft chain introduced therein”.
[Method of Forming Surface Graft]
For forming an ionic surface of a graft polymer on the support, employable is any known method. Specifically, those methods described in the
Journal of the Rubber Association of Japan
, Vol. 65, p. 604, 1992, “Surface Modification and Adhesion with Macromonomer” by Shinji Sugii, for example, may be employed. In addition, a surface-grafting polymerization method described below may also be suitably used.
[Description of Surface-Grafting Method]
The surface formed by the surface-grafting method refers to a polymer surface grafted with monomer molecules in any known manner of exposing the polymer surface to light, electronic radiation, heat or the like. The monomer may be any of those positively charged with ammonium, phosphonium or the like, or those having a negatively-charged acidic group or an acidic group capable of being dissociated into a negatively-charged group, such as a sulfonic acid group, a carboxyl group, a phosphoric acid group or a phosphonic acid group, or may even be a monomer having a nonionic group such as a hydroxyl group, an amido group, a sulfonamido group, an alkoxy gro
Kawamura Koichi
Takahashi Miki
Yamasaki Sumiaki
Ashton Rosemary
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Gilliam Barbara
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