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
2001-07-02
2004-04-06
Hamilton, Cynthia (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
C430S280100, C430S270100, C430S944000, C430S912000, C430S176000, C430S177000, C430S964000, C430S914000, C430S921000, C430S925000, C430S927000, C430S916000, C430S288100, C430S281100, C430S285100, C430S284100, C430S283100
Reexamination Certificate
active
06716566
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a negative planographic printing plate which can manifest a so-called direct process in which preparation can be directly effected by scanning with infrared laser based on digital signals from computers and the like.
2. Description of the Related Art
Recently, there are remarkable developments in lasers. Particularly, solid laser and semiconductor laser which emit an infrared ray having a wavelength from 760 nm to 1200 nm and show high output and have small size are easily available. These lasers are very useful as a recording light source in direct preparation of planographic printing plates based on digital data from computers and the like. However, a lot of photosensitive recording materials which are practically useful have photosensitive wavelengths in visible range of not more than 760 nm, therefore, images can not be recorded by these infrared lasers. Thus, material which can be recorded by infrared laser are desired.
As such image recording materials which can be recorded by infrared laser, there is a recording material composed of an onium salt, phenol resin and spectral sensitizing agent described in U.S. Pat. No. 4,708,925. This image recording material is a positive image recording material utilizing an effect of suppressing dissolution into a developing solution, the effect being manifested by the onium salt and phenol resin, and is not a negative material as embodied in the present invention. On the other hand, as the negative image recording material, U.S. Pat. No. 5,340,699 describes a recording material composed of an infrared absorber, acid generator, resol resin and novolak resin. However, such a negative image recording material requires, for forming image, heating treatment after exposure to laser, therefore, a negative image recording material requiring no heating treatment after exposure has been desired.
For example, JP-B No. 7-103171 describes a recording material requiring no heating treatment after image-wise exposure, the material being composed of a cyanine pigment having a specific structure, an iodonium salt and an addition-polymer izable compound having an ethylenically unsaturated double bond. However, in the case of this image recording material, there are problems that when a photosensitive layer application solution is applied, a uniform photosensitive layer is not formed easily due to non-uniformity in film thickness caused by contact with an application means such as a bar coater and the like, and when a photosensitive layer is formed and stored immediately without exposure and preparation, long-term stability is not sufficient, and sensitivity lowers with the lapse of time.
For enhancing uniformity of a photosensitive layer, there are investigations on compounding of various surfactants into an application solution. However, use of usual nonionic surfactants do not easily allow sensitivity to be stable with the passage of time, and in the case of use of fluorine-based surfactants, although relatively uniform coated films are obtained, there is a problem that fluorine-based surfactants which have been localized on the surface of the photosensitive layer immediately after application and drying mix with the photosensitive layer with the lapse of time, resultantly, leading to reduction in sensitivity. That is, in current situations, there is no means found yet which does not lower the property of a photosensitive layer, improve the face flatness of the formed photosensitive layer, and can suppress reduction in sensitivity with the lapse of time.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a negative planographic printing plate which can be directly recorded based on digital data from computers and the like by conducting recording using solid laser and semiconductor laser emitting an infrared ray, excellent in storage stability, reveals no reduction in sensitivity with the lapse of time, and has excellent face flatness.
The present inventors have directed their attention to the property of a surfactant used in a recording layer application solution for a negative planographic printing plate, and intensively studied this. As a result, they found that a recording layer having excellent and uniform face flatness and having excellent long-term stability can be obtained by using a silicon-based surfactant which is one kind of organometal-based surfactants, thus leading to completion of the present invention.
Namely, the negative planographic printing plate of the present invention can be recorded by infrared laser, and has a constitution in which a photosensitive layer which is obtained by applying and drying a photosensitive layer application solution containing an infrared absorber, a compound which generates a radical or acid due to heat, a polymerizable compound or crosslinking compound, and a silicon-based surfactant, and which is hardened by exposure to infrared laser, is provided on a substrate.
In the planographic printing plate of the present invention, it may be advantageous that at least a photosensitive layer is formed on a substrate, and other layers, for example, an intermediate layer, overcoat layer, backcoat layer and the like, can be provided according to the object, providing they do not deteriorate the effect of the present invention.
Although the action of the present invention is not explicit, it is speculated that a silicon-based surfactant contained in a photosensitive layer application solution manifests high surface activity even at low concentration and is useful for solubilizing an organic solvent and polymer and for dispersing and stabilizing an infrared absorber, and due to high surface tension of the application solution, the solution surface is quickly smoothed immediately after application of a photosensitive layer on a substrate, thus excellent face flatness is obtained. Further, as a solvent of a photosensitive layer application solution is removed while applying and drying, the silicon-based surfactants become localized on and near the surface of a photosensitive layer, and permeation of moisture from air through the surface into a photosensitive layer can be suppressed by action of hydrophobic group of the surfactants. Consequently, it is also advantageous in storage of a plate that lowering in sensitivity with reduction in light-heat conversion efficiency due to permeation of moisture into a photosensitive layer can be efficiently prevented, and that sliding property on the surface of a photosensitive is improved and scratch-resistance in storage is enhanced.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in detail below.
The feature of the present invention is the inclusion of a silicon-based surfactant in a photosensitive layer.
[Silicon-Based Surfactant]
Examples of the silicon-based surfactant used in the photosensitive layer application solution of the present invention include surfactants having Si in the main chain of the molecule. Any of cationic surfactants such as amine salts, quaternary ammonium salts and the like, nonionic surfactants containing an alkylene oxide in the main chain, so-called silicon-based surfactants having a siloxane skeleton, and the like may be used.
Since the various functions of the silicon-based surfactant such as a surface activity, ability to solubilize an organic solvent, ability to stabilize dispersion of solid fine particles such as a pigment and the like differ in accordance with the kinds and numbers of hydrophilic groups and hydrophobic groups included therein, and the like, the silicon-based surfactant is appropriately selected in view of affinity with various components used in a photosensitive layer, required surface activity, dispersing property, and the like. Generally, from the standpoint of effects, nonionic surfactants are preferable, and among them, silicone-based surfactants typified by a siloxane/oxyethylene copolymer are preferable.
Examples of the silicon-based surfactant which can be u
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
Hamilton Cynthia
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