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
2000-09-28
2003-08-19
Baxter, Janet (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, C101S453000, C101S457000, C101S463100
Reexamination Certificate
active
06607866
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a lithographic printing plate support provided with a novel hydrophilic layer, and to a lithographic printing plate precursor using such a support. In particular, the invention is concerned with a lithographic printing plate support which enables the adoption of both positive-working and negative-working modes and ensures excellent sensitivity and scum resistance, and to a lithographic printing plate precursor using such a support.
BACKGROUND OF THE INVENTION
Hitherto employed hydrophilic substrates or hydrophilic layers for lithographic printing plates are anodically oxidized aluminum substrates, or substrates or hydrophilic layers prepared by treating anodized aluminum substrates with subbing agents, such as silicate, polyvinyl phosphonic acid (JP-A-7-1853, wherein the term “JP-A” means an “unexamined published Japanese patent application”) and polyvinyl benzoic acid, for the purpose of further enhancing their hydrophilicity. There are a growing number of researches on hydrophilicity-imparted substrates or supports and hydrophilic layers in the case of using an aluminum support. In addition, the art of using a sulfonic acid group-containing polymer for the subbing layer of a photosensitive layer is disclosed in JP-A-59-101651.
As to the hydrophilic layer provided in the case of using a flexible support, such as a PET (polyethylene terephthalate) or cellulose acetate film, in place of a metal support such as an aluminum sheet, the art of forming a hydrophilic layer from a hydrophilic polymer and a hydrophobic polymer to impart swelling properties to the layer is known by the description in JP-A-8-292558, the art of covering the surface of a PET support with micro-porous hydrophilic cross-linked silicate is known by the description in European Patent 0 709 228, and the art of curing a hydrophilic polymer-containing hydrophilic layer with a hydrolyzed tetraalkyl orthosilicate is known by the descriptions in JP-A-8-272087 and JP-A-8-507727.
While those hydrophilic layers provide lithographic printing plates by the use of which scum-free prints can be obtained at the beginning of printing, it has been expected from the practical point of view to further heighten the hydrophilicity of a hydrophilic layer and to develop lithographic printing plate precursors capable of providing scum-free prints under severer printing conditions also.
SUMMARY OF THE INVENTION
Therefore, an object of the invention is to solve the aforementioned current problems and, more specifically, to provide a support for a positive-working or negative-working lithographic printing plate, which has a hydrophilic layer having high hydrophilicity and high bonding power to a support to enable particular improvement in printing scum resistance, thereby ensuring scum-free prints even under severe printing conditions, and further to provide a lithographic printing plate precursor using such a support.
In order to attain the aforementioned objects, we have made intensive studies on hydrophilic layers that have high hydrophilicity and don't peel off the substrate thereof. As a result, it has been found that scum-free prints can be obtained even under severe printing conditions by the use of a polymer compound layer prepared by subjecting, for example, a PET film surface to glow treatment (irradiation with oxygen plasma in vacuo), thereby inducing active species such as radicals on the PET film surface, and then adding a hydrophilic group-containing monomer capable of initiating the reaction with the active species to cause graft polymerization on the film surface, namely a hydrophilic layer chemically bonded to the film substrate at the polymer chain end.
In other words, the invention comprises the following embodiments (1) to (8):
(1) A lithographic printing plate support, comprising a support and a hydrophilic layer on the support, wherein the hydrophilic layer comprises a polymer compound that is chemically bonded directly to the support surface and has a hydrophilic functional group.
(2) The lithographic printing plate support as described in (1) above, wherein said polymer compound is a hydrophilic functional group-containing straight-chain polymer compound that is chemically bonded directly to the support surface at an end of the polymer chain.
(3) The lithographic printing plate support as described in (1) above, wherein said polymer compound is a polymer compound comprising (a) a polymer backbone chemically bonded to the support surface and (b) a hydrophilic functional group-containing straight-chain polymer compound combined at an end of a polymer chain thereof with the polymer backbone.
(4) A lithographic printing plate precursor comprising a support, a hydrophilic layer and an image-forming layer in this order, wherein the hydrophilic layer comprises a polymer compound that is chemically bonded directly to the support surface and has a hydrophilic functional groups.
(5) The lithographic printing plate precursor as described in (4) above, wherein said polymer compound is a hydrophilic functional group-containing straight-chain polymer compound that is chemically bonded directly to the support surface at an end of the polymer chain.
(6) The lithographic printing plate precursor as described in (4) above, wherein said polymer compound is a polymer compound comprising (a) a polymer backbone chemically bonded to the support surface and (b) a hydrophilic functional group-containing straight-chain polymer compound combined at an end of a polymer chain thereof with the polymer backbone.
(7) A lithographic printing plate precursor comprising a support, a hydrophilic layer and a sensitive layer in this order, wherein the hydrophilic layer comprises a polymer compound that is chemically bonded directly to the support surface and has a hydrophilic functional group and the sensitive layer comprises a polymer compound containing a functional group capable of changing the hydrophobic or hydrophilic property upon exposure to heat, acid or radiation.
(8) A lithographic printing plate precursor comprising a support, a hydrophilic layer comprising a polymer compound that is chemically bonded directly to the support surface and has a hydrophilic functional group and on the hydrophilic layer an ablative ink-receiving layer.
The problems have been solved, as described above, by adopting as the art of making use of very high hydrophilicity the hydrophilic layer formed of a hydrophilic polymer grafted on the support surface. More specifically, the resolution of problems becomes feasible by preparing a lithographic printing plate support provided with a hydrophilic layer that is formed of a polymer compound containing hydrophilic functional groups and chemically bonded to the support surface, wherein the polymer compound is chemically bonded to the support surface directly at its polymer chain end or via a polymer backbone chemically bonded to the support surface, and further preparing a lithographic printing plate precursor using the aforesaid support.
Further, it is already known that the hydrophilicity of a hydrophilic layer can be enhanced by increasing the water-receptivity in the hydrophilic layer. However, conventional hydrophilic layers have a problem that, when it is tried to increase the water-holding capacity therein, they always come to have an increased degree of swelling and become weak in structure to result in the lowering of their film strength or the deterioration of adhesiveness to supports.
When the hydrophilic layer characteristic of the invention, which is formed of the hydrophilic functional group-containing polymer compound chemically bonded directly to a support surface, takes the form of surface hydrophilic graft polymer, the polymer chain has a restraint-free structure, except that it is bound to the support surface, so that water is easy to get into the hydrophilic layer. Therefore, the present hydrophilic layer is characterized by its great water-holding capacity. Indeed, it is reported in literature that the surface hydrophilic graft polymers
Aoshima Norio
Kawamura Koichi
Oda Akio
Yamasaki Sumiaki
Baxter Janet
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Gilliam Barbara
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