Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1998-09-14
2001-01-30
Krynski, William (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S478200, C428S500000, C428S503000, C428S913000, C525S330300
Reexamination Certificate
active
06180213
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a planographic printing plate material which does not require liquid development, and particularly to a planographic printing plate material providing a planographic printing plate preventing image portions on the plate from dissolving during printing.
BACKGROUND OF THE INVENTION
A printing plate is ordinarily prepared by exposing to light a presensitized planographic printing plate and developing the exposed plate with liquid developer. This process, however, produces waste liquid developer which must be discarded, resulting in environmental problems.
Recently, a method (dry plate-making process) for making a printing plate without employing liquid developer has been studied, and various methods have been proposed for the dry plate-making process,
For example, there is proposed a method of preparing a planographic printing plate according to a transfer method, however, this method has a problem of producing image defects. Further, there is proposed a method preparing a planographic printing plate according to an ablation method, however, this method has a problem in that the ablated scatters and soils the surroundings, and further a specific development machine is required for forming an image in a closed system.
To the contrary, physical property change type planographic printing plate material is preferable which can form an image employing oleophile-hydrophile property change, since this material makes it possible to prepare a planographic printing plate without liquid development.
Various physical property change type planographic printing plate materials have been proposed. For example, in Japanese Patent O.P.I. Publication No. 62-164049 is disclosed a planographic printing plate material comprising a hydrophilic support, and provided thereon, a recording layer containing a block isocyanate and an active hydrogen-containing resin capable of reacting with an isocyanate, wherein the support or the recording layer contains a light-heat converting compound. This technique provides improved durability at exposed portions, since isocyanate produced by heat application reacts with the resin, however, this comprises a developing step of dissolving unexposed portions with a liquid developer. When a planographic printing plate prepared from this material without liquid development after exposure is used, it produces dissolution of non-exposed portions and stains on dampening rollers during printing, resulting in adverse effects on the printing properties.
A method employing capsules was proposed, but the method has a problem of resolving power resulting from the capsule size.
In Japanese Patent O.P.I. Publication No. 51-63704 is disclosed a method of preparing a planographic printing plate, imagewise exposing to laser a planographic printing plate material without any further treatment after exposure, which has, on a support, a hydrophilic layer containing dyes and a non-light sensitive compound such as PVP, PVA, casein, dextrin, gum arabic, HEC, PEG, polyacrylic acid, or PVPA. However, this method is not necessary satisfactory, since it has problems of low sensitivity and high noise.
In U.S. Pat. No. 4,081,572 is disclosed a physical property change type planographic printing plate material comprising a support, and provided thereon, a hydrophilic layer containing a specific hydrophilic polymer, in which the hydrophilic layer is made hydrophobic by imagewise energy exposure. In this case, change from the hydrophilic to hydrophobic layer at image portions is realized by decarboxylation of the hydrophilic polymer, and therefore, strength of the image portions and the non-image portions is not sufficient, resulting in lowering of printing durability.
In view of the above, the present invention has been made. The present invention provides a planographic printing plate prepared by a dry plate-making process, and provides a planographic printing plate material which is inexpensive, and gives improved sensitivity, S/N, and strength at image portions and non-image portions, and high resolving power.
SUMMARY OF THE INVENTION
A first object of the invention is to provide a heat sensitive planographic printing plate material, which can provide a planographic printing plate through dry plate-making process, without requiring discarding treatment of a waste solution, and through a shortened planographic printing plate preparing process, and an image forming method employing the material.
A second object of the invention is to provide a heat sensitive planographic printing plate material with high sensitivity which can provide a planographic printing plate without stop stains, and with high strength at image portions and non-image portions, excellent printing durability, high water tolerance, and high resolving power, and an image forming method employing the material.
DETAILED DESCRIPTION OF THE INVENTION
The above objects can be attained by the following:
1. A heat sensitive planographic printing plate material comprising a support and provided thereon, a heat sensitive layer, wherein the heat sensitive layer contains at least one hydrophilic resin selected from the group consisting of gelatin, polyvinyl alcohol and carboxymethyl cellulose in an amount of 10 to 98 weight %, and a cross-linking agent in an amount of 2 to 50 weight %.
2. The heat sensitive planographic printing plate material of item 1 above, wherein the heat sensitive layer further contains a light-heat converting agent.
3. The heat sensitive planographic printing plate material of item 2 above, wherein the light-heat converting agent is a near-infrared absorbent.
4. The heat sensitive planographic printing plate material of item 3 above, wherein the near-infrared absorbent is selected from the group consisting of carbon black, a cyanine dye, and a polymethine dye.
5. The heat sensitive planographic printing plate material of item 1 above, further comprising a light-heat converting layer containing a light-heat converting agent.
6. The heat sensitive planographic printing plate material of item 1, 2, 3, 4 or 5 above, wherein the cross-linking agent is at least one selected from the group consisting of an amino resin, an amino compound, an aziridine compound, and aldehydes.
7. The heat sensitive planographic printing plate material of item 1, 2, 3, 4, 5 or 6 above, wherein the heat sensitive layer further contains a reaction accelerating agent.
8. The heat sensitive planographic printing plate material of item 1 above, wherein the heat sensitive layer has a dry thickness of 0.01 to 15 &mgr;m.
9. The heat sensitive planographic printing plate material of item 1, 2, 3, 4, 5, 6, 7 or 8 above, wherein after the material is immersed in 25° C. water for 1 hour, the dissolution amount of the heat sensitive layer is 10 weight % or less based on the weight of heat sensitive layer before the immersion.
10. The heat sensitive planographic printing plate material of item 1, 2, 3, 4, 5, 6, 7 or 8 above, wherein the material is subjected to heat treatment so that a dissolution amount of the heat sensitive layer after immersed in 25° C. water for 1 hour is 10 weight % or less based on the weight of heat sensitive layer before the immersion.
11. A method of manufacturing the heat sensitive planographic printing plate material of item 1, 2, 3, 4, 5, 6, 7 or 8 above, the method comprising the steps of coating on a support a heat sensitive layer containing at least one hydrophilic resin selected from the group consisting of gelatin, polyvinyl alcohol and carboxymethyl cellulose, in an amount of 10 to 98 weight %, and a cross-linking agent in amount of 2 to 50 weight %, which cross-links the hydrophilic resin; and then drying the coated heat sensitive layer by entirely heating so that a dissolution amount of the heat sensitive layer after immersed in 25° C. water for 1 hour is 10 weight % or less based on the weight of heat sensitive layer before the immersion.
12. A method of forming an image, the method comprising the steps of heating the heat sensitive planographic printing plate materi
Akiyama Takeo
Akiyama Yasuo
Hiraoka Saburou
Kojima Yasuo
Kuroki Takaaki
Akiyama Yasuo
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Konica Corporation
Krynski William
Shewareged B.
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