Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied after imaging
Reexamination Certificate
2001-07-23
2003-07-01
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied after imaging
C430S204000, C430S218000, C430S264000, C430S383000, C430S391000, C430S543000, C430S552000, C430S553000, C430S554000, C430S555000, C430S556000, C430S558000, C430S559000, C430S620000, C430S619000
Reexamination Certificate
active
06586167
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for thermally forming images for plate making and a thermally processed image recording material for plate making. More precisely, the present invention relates to a thermally processed image recording material for plate making that can be used as an intermediate material in printing plate making, further specifically a thermally processed image recording material for plate making that is used for output of an edited original on a film and subsequent printing of formed images on a printing plate such as PS plates, as well as a method for thermally recording images for plate making using the thermally processed image recording material for plate making.
RELATED ART
Methods for forming images utilizing thermally processed image recording materials using silver salts of organic acids are described in, for example, U.S. Pat. Nos. 3,152,904 and 3,457,075 and D. Klosterboer, “Thermally Processed Silver Systems”, Imaging Processes and Materials, Neblette, 8th ed., compiled by J. Sturge, V. Walworth and A. Shepp, Chapter 9, p. 279, (1989). Such thermally processed image recording materials comprise a reducible non-photosensitive silver source (e.g., silver salt of an organic acid), a photocatalyst (e.g., silver halide) in a catalytically active amount and a reducing agent for silver, which are usually dispersed in an organic binder matrix. While the photosensitive materials are stable at an ordinary temperature, when they are heated to a high temperature (e.g., 80° C. or higher) after light exposure, silver is produced through an oxidation-reduction reaction between the reducible silver source (which functions as an oxidizing agent) and the reducing agent. The oxidation-reduction reaction is accelerated by catalytic action of a latent image generated upon exposure. The silver produced from the reaction of the reducible silver salt in the exposed areas provides silver images and hence contrast with respect to the non-exposed areas, and thus images are formed.
The aforementioned image recording materials and image forming methods can be used for making printing plates. A method for recording images for printing plate making comprises steps of drawing images with laser lights or the like, developing the images to form silver images, and printing the images on a printing plate with a ultraviolet ray at 350-450 nm using the images as a mask to reproduce the images on the printing plate utilizing the transmission of the UV ray through portions other than the portions where the silver images that shield the UV ray are not formed. Therefore, it is desirable that the image recording material for plate making used for the production of mask should show significant difference of transmission for ultraviolet rays between the image areas and the non-image areas.
A thermally processed image recording material utilizing a silver salt of an organic acid must preliminarily contain all of the materials required for the image formation in its films, and such materials remain in the films as original chemical species or reaction products thereof even after the heat development. It is so far attempted to make the image recording material substantially colorless by devising the substances so that they should not show absorbance for the visible region and thus they should not be obstacles to visual observation of the images. However, in such a purpose for printing plate making, the substances are further desired to show low absorbance for ultraviolet rays. In thermally processed materials, it has been a big technical problem to maintain UV absorbance of non-image areas to be low and increase UV absorbance of image areas, since the materials contain many kinds of substances and organic substances generally show absorbance in the ultraviolet region though the degree may be different.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the aforementioned problems of the prior art. That is, the object to be achieved by the present invention is to provide a thermally processed image recording material and method for thermally forming images that provide significant difference of ultraviolet absorption between image areas and non-image areas suitable for printing plate making.
The inventors of the present invention assiduously studied in order to achieve the aforementioned object. As a result, they found that a superior thermally processed image recording material and method for thermally forming images that provide the desired effect can be obtained by using a reducing agent and a color image forming material in combination in a thermally processed image recording material to form an image consisting of a developed silver image and color forming dye image so that the color forming dye image should show an absorbance for ultraviolet region higher than that for visible region and have a transmission density of 0.3 or more for the region of 360-450 nm. Thus, they accomplished the present invention.
That is, the present invention provides a method for thermally forming images for plate making, which comprises forming an image for plate making by using a thermally processed image recording material comprising a silver salt of an organic acid, a reducing agent, a color image forming material and an organic binder on a support, wherein the image consists essentially of a developed silver image and a color forming dye image and the color forming dye image shows an absorbance for ultraviolet region higher than that for visible region and has a transmission density of 0.3 or more for the region of 360-450 nm.
According to another aspect of the present invention, there is provided a thermally processed image recording material for plate making comprising a silver salt of an organic acid, a reducing agent, a color image forming material and an organic binder on a support, which forms an image consisting of a developed silver image and a color forming dye image, and in which the color forming dye image shows an absorbance for ultraviolet region higher than that for visible region and has a transmission density of 0.3 or more for the region of 360-450 nm.
Preferably, the organic binder is a hydrophobic thermoplastic organic polymer.
Preferably, the organic binder consists of polymer latex dispersed in water.
Preferably, the reducing agent consists of microparticles solid-dispersed in water.
Preferably, the reducing agent consists of a compound represented by the formula Q
1
—NHNH—Q
2
wherein Q
1
represents an aromatic group or 5- to 7-membered unsaturated ring bonding to —NHNH—Q
2
at a carbon atom, and Q represents a carbamoyl group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a sulfonyl group or a sulfamoyl group.
Preferably, a thermally processed image recording material containing a halogen precursor is used.
Preferably, the halogen precursor consists of microparticles solid-dispersed in water.
Preferably, the color image forming material is a compound represented by any one of the following formulas (1) to (18):
wherein, in the formulas (1) to (18), X
1
to X
18
each independently represents a hydrogen atom or a substituent; in the formula (1), R
1
and R
2
each independently represent an electron withdrawing group; in the formulas (2) to (18), R
3
to R
35
each independently represent a hydrogen atom or a substituent, m, n, p and q each independently represent an integer of 0-4; and r represents an integer of 0-5.
Preferably, the color image forming material is in the form of solid-dispersed microparticles.
Preferably, the color image forming material is of divalent type.
Preferably, the thermally processed image recording material for plate making of the present invention contains an ultrahigh contrast agent.
According to the present invention, it became possible to provide a thermally processed image recording material and method for thermally forming images that give a large difference in ultraviolet absorption between image areas and non-image areas, which is suitable for printing plate making.
DETAILED EXPLANA
Katoh Kazunobu
Oya Toyohisa
Chea Thorl
Fuji Photo Film Co. , Ltd.
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