COLOR IMAGE FORMING METHOD USING
SILVER HALIDE, REDUCING AGENT,
POLYMERIZABLE COMPOUND AND
COLORANT 5
FIELD OF THE INVENTION
The present invention relates to an image forming method using a polymerization reaction initiated by silver halide. The invention also relates to an image forming method using a light-sensitive material which can be imaged with a scanning light such as a laser bean. The invention further relates to an image forming method which is advantageously used for forming a color proof.
BACKGROUND OF THE INVENTION
As the computer technology has recently been developed, a technical innovation is greatly introduced in 2Q printing. The field of color printing is now digitized by using a computer system named as CEPS (Color Electronic Preptess System). The CEPS digitizes the printing data of a color image and the data of all the preptess process down to stripping. Further, the newest system ^ directly outputs the digitized printing data to a presensitized printing plate of a high sensitivity to prepare a printing plate without use of a conventional lith film. The technical innovation in the printing field makes the lith film unnecessary. 30
Before running on, a proofread is necessary to inspect the finished quality of printing. The proofing systems include a pressproof and an analogue offpress proof. The pressproof comprises preparing a printing plate for a proof sheet and printing an image using a proof press. 35 The analogue offpress proof employs an image forming system different from the printing system. The offpress proof system comprises uniformly exposing to light a light-sensitive material through a lith film. The lightsensitive material contains a photopolymer, and the 40 light source usually is ultraviolet. These two proofing systems are based on the premise that the printing system uses a lith film. The proof sheet itself is prepared from the image on the lith film (cf., M. H. Bruno, Principle of Color Proofing). 45
As is mentioned above, the conventional proofing systems are based on use of the lith film. Now, it is an important problem how to inspect the printing quality when the technical innovation in the printing field makes the lith film unnecessary. Therefore, the newest 50 printing system requires a proof system of preparing a proof sheet directly from digital image data without use of the lith film. The required proof system is named as DDCP (Digital Direct Color Proof). With respect to the DDCP, several systems have been proposed, and 55 some of them are practically used.
The DDCP systems employ an electrophotography and a thermal transfer recording system, which are completely different from the conventional analogue offpress proof using a photopolymer. The proofing 60 qualities of DDCP (such as resolving power, color tone, gradation, reproducibility of half tone, analogy to printing and stable reproducibility of the image) are insufficient compared with the conventional systems. The image qualities of the direct output from a digital image 65 are not satisfied. Therefore, an improved proofing method which can directly output the digital image is required to obtain a color proof of high quality.
Japanese Patent Publication No. 48(1973)-31323, Japanese Patent Provisional Publications No. 59(1984)-97140, No. 62(1987)-267736, No. 2(1990)-244151 and U.S. Pat. No. 3,770,438 disclose an analogue offpress proof using a conventional photopolymer. If the digital image data can directly be recorded on the offpress proof using the photopolymer, the proofing qualities are probably satisfactory. However, the digital image data should be recorded on a light-sensitive material for proof by a scanning exposure using a specific light source such as a laser bean. Therefore, the light-sensitive material should have a high sensitivity to the wave length of the scanning light. The conventional light-sensitive material using a photopolymer does not have such a high sensitivity. Further, it is particularly difficult to sensitize the photopolymer to a laser beam of a long wave such as a He-Ne laser and a semiconductor laser. The photopolymer merely has a sensitivity to a laser beam of a short wave. Accordingly, the conventional analogue offpress proof is not available in the DDCP systems.
In conclusion, the offpress proof using a photopolymer cannot directly record the digital image data, since the photopolymer does not have a high sensitivity to the wave length of the scanning light (particularly a laser beam of a long wave). On the other hand, the proofing qualities of the conventional DDCP systems (using an electrophotography or a thermal transfer recording system) are insufficient with respect to resolving power, reproducibility of half tone or stable reproducibility of color. Therefore, a new DDCP method is required to record a color proof of high quality with a high sensitivity to the wave length of a scanning light.
By the way, Japanese Patent Provisional Publications No. 61(1986)-69062 and No. 61(1986)-73145 (the contents of these two publications are described in U.S. Pat. No. 4,629,676 and European Patent Provisional Publication No. 0174634A) discloses an image forming method using a light-sensitive material which contains silver halide, a reducing agent and a polymerizable compound. The method comprises the steps of imagewise exposing to light the light-sensitive material, and heating the material to develop the silver and to harden imagewise the polymerizable compound. Thus a polymer image is formed on the light-sensitive material. In a representative embodiment of the method, the developed light-sensitive material (containing a colorant) is pressed on an image receiving material to transfer the colorant with the unpolymerized polymerizable compound to the image receiving material. Thus a color image is formed on the image receiving material. In the case that a multi-color image is formed on the image receiving material, the light-sensitive material should contain two or more kinds of microcapsules (or packet emulsions) each containing a colorant different from each other.
SUMMARY OF THE INVENTION
The present inventors paid attention to the image forming method using a polymerization reaction initiated by silver halide, and have tried to apply the method to formation of a color proof. However, the inventors note some problems when the image forming method itself is applied to the color proof.
For example, there are the following problems (1) to (4) where a multicolor image is formed by using two or more kinds of microcapsules each containing a colorant different from each other.
(1) Using the microcapsules, the resolving power of the light-sensitive material is limited to the size of the microcapsules.
(2) The microcapsules are ruptured by pressure to form an image. The resolving power is more degraded 5 than the size of the microcapsules, since the contents of the microcapsules are spread by the pressure.
(3) The amount of the colorant contained in the microcapsule is severely limited. Accordingly, the maximum density of the image is low. 1°
(4) The printed matter has overlap of color (ink). The method using microcapsules cannot reproduce the overlap.
An object of the present invention is to improve the image forming method using a polymerization reaction 15 initiated by silver halide and to provide a method advantageously used for forming a color proof.
Another object of the invention is to provide an image forming method which can form a color proof directly from digital image data without use of a lith film.
A further object of the invention is to provide an image forming method which forms a color proof of a high quality by a scanning exposure with a laser beam, particularly a laser beam of a long wave.
A still further object of the invention is to provide an image forming method which can form a hardened image with a low exposure energy, whereby a color proof is made from the hardened image 30
The present invention provides an image forming method comprises the four embodiments. Each of the embodiments is a method which uses a light-sensitive material and an image receiving material. The light-sensitive material comprises a support and a light-sensitive j5 polymerizable layer. The light-sensitive polymerizable layer contains silver halide, a reducing agent, an ethylenically unsaturated polymerizable compound or/and a cross-linkable polymer and a colorant.
The first embodiment comprises the steps of: 40
(1) imagewise exposing to light the light-sensitive polymerizable layer (hereinafter referred to as an exposing step);
(2) developing the light-sensitive polymerizable layer
to harden the ethylenically unsaturated polymerizable 45 compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (hereinafter referred to as a developing step);
(3) placing the light-sensitive material in contact with the image receiving material to transfer the unhardened 50 area to the image receiving material whereby a color image is formed on the image receiving material (hereinafter referred to as a transferring step); and then
(4) repeating the steps (1) to (3) using light-sensitive materials each having a color different from each other, 55 to form a multicolor image on the image receiving material (hereinafter referred to as a repeating step).
The second embodiment comprises the steps of:
(1) imagewise exposing to light the light-sensitive polymerizable layer (an exposing step); 60
(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area"(a developing step); 65
(3) placing the light-sensitive material in contact with the image receiving material to transfer the hardened area to the image receiving material whereby a color
image is formed on the image receiving material (a transferring step); and then
(4) repeating the steps (1) to (3) using light-sensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (a repeating step). The third embodiment comprises the steps of: (A) laminating the light-sensitive material on the image-receiving material (hereinafter referred to as a laminating step);
(1) imagewise exposing to light the light-sensitive polymerizable layer (an exposing step);
(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (a developing step);
(3) peeling the image receiving material from the light-sensitive material to transfer the unhardened area to the image receiving material whereby a color image is formed on the image receiving material (hereinafter referred to as a transferring step); and
(4) repeating the steps (A) and (1) to (3) using lightsensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (a repeating step),
wherein the order is selected from: (A)-Kl)->(2)-K3)-K4); and (1)-^A)-K2)-K3)-K4). The fourth embodiment comprises the steps of: (A) laminating the light-sensitive material on the image-receiving material (a laminating step);
(1) imagewise exposing to light the light-sensitive polymerizable layer (an exposing step);
(2) developing the light-sensitive polymerizable layer to harden the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer within the exposed area or, in the alternative, within the unexposed area (a developing step);
(3) peeling the image receiving material from the light-sensitive material to transfer the hardened area to the image receiving material whereby a color image is formed on the image receiving material (a transferring step); and
(4) repeating the steps (A) and (1) to (3) using lightsensitive materials each having a color different from each other, to form a multicolor image on the image receiving material (a repeating step),
wherein the order is selected from: (AM1H2H3H4); and (l)-KA)-K2)-*(3)-K4).
In the four embodiments, the light-sensitive polymerizable layer preferably comprises a light-sensitive layer containing the silver halide and a polymerizable layer containing the ethylenically unsaturated polymerizable compound or/and the cross-linkable polymer and the colorant.
The reducing agent may be contained in the light-sensitive layer or/and the polymerizable layer. Further, the light-sensitive polymerizable layer may comprise a light-sensitive layer, a polymerizable layer and an image formation accelerating layer. The reducing agent may also be contained in the image formation accelerating layer. In the present specification, the light-sensitive polymerizable layer comprising two or more functional layers is referred to as "a complex light-sensitive polymerizable layer". A light-sensitive material having the complex light-sensitive polymerizable layer is referred
to as "a multi-layered light-sensitive material". On the other hand, a light-sensitive material having a single light-sensitive polymerizable layer is referred to as "a single-layered light-sensitive material".
In the first and second embodiments, a polymerizable 5 layer is provided on a support, and a light-sensitive layer is provided thereon. In the third and fourth embodiments, a light-sensitive layer is provided on a support, and a polymerizable layer is provided thereon.
When a multi-layered light-sensitive material is used 10 in the first and second embodiments, the light-sensitive layer should be removed before the developing step and the transferring step. In the case that layers other than the light-sensitive layer and the polymerizable layer are provided on a support, a layer provided on or above the 15 polymerizable layer should also be removed.
In the present invention, two or more steps can be conducted simultaneously provided that the abovedefined order is not reversed. For example, the exposing step (1) can be conducted simultaneously with the 20 developing step (2). A process conducting two or more steps simultaneously is included within the scopes of the present invention.
The image forming method is characterized in that the steps are repeated using light-sensitive materials 25 each having a color different from each other, to form a multicolor image on the image receiving material. This method has the following advantages (1) to (4) compared with the previous method using microcapsules. 30
(1) Using the microcapsules, the resolving power of the light-sensitive material is limited to the size of the microcapsules. There is no such limitation on the method of the invention.
(2) The microcapsules are ruptured by pressure to 35 form an image. The resolving power is more degraded than the size of the microcapsules, since the contents of the microcapsules are spread by the pressure. There is no such problem on the method of the invention.
(3) The amount of the colorant contained in the mi- 40 crocapsule is severely limited. On the other hand, a relatively large amount of the colorant can be contained
in the light-sensitive material. Therefore, a high maximum density of an image can be obtained according to the present invention. 45
(4) The printed matter has overlap of color (ink). The method using microcapsules cannot reproduce the overlap. The method of the invention can reproduce the overlap by repeating the above-mentioned steps where the color of the colorant or toner corresponds to the 50 color of the ink in the printed matter. Therefore, the present invention can form an excellent color proof having a color tone which is very similar to that of the printed matter.
Thus the problem of the image forming method using 55 a polymerization reaction initiated by silver halide is solved by the present invention. This method now can be applied to formation of a color proof.
Therefore, a color proof can be formed directly from digital image data without use of a lith film. Further, a 60 color proof of a high quality can be formed by a scanning exposure with a laser beam, particularly a laser beam of a long wave. Furthermore, a hardened image can be formed with a low exposure energy
Further, the following effects can be obtained by 65 using the specific embodiments of the present invention.
1. In the second and fourth embodiments, the hardened area is transferred to the image receiving material.
The hardened area is mechanically strong compared with the unhardened area. Therefore, the reproducibility of a minute image such as a half tone is improved in the second and fourth embodiment to form a clear image.
2. In the third and fourth embodiments of the invention, the light-sensitive material is laminated on the image-receiving material. These embodiments have an advantage of easy adjustment and easy operation with respect to the setting of an image.
3. In the multi-layered light-sensitive material having a light-sensitive layer and a polymerizable layer, silver halide does not influence on the color tone of the polymerizable layer.
Further, the components of the light-sensitive layer such as silver halides are not contained in the polymerizable layer. Therefore, the polymer image formed in the polymerizable layer has a high mechanical strength, since the polymerizable layer substantially consists of only the polymerizable compound or the cross-linkable polymer. A clear color image can be formed from the strong polymer image.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view schematically illustrating a single-layered light-sensitive material used in the image forming method of the present invention.
FIG. 2 is a sectional view schematically illustrating another embodiment of a single-layered light-sensitive material used in the image forming method.
FIG. 3 is a sectional view schematically illustrating a multi-layered light-sensitive material used in the first and second embodiments of the image forming method.
FIG. 4 is a sectional view schematically illustrating a multi-layered light-sensitive material used in the third and fourth embodiments of the image forming method.
FIG. 5 is a sectional view schematically illustrating the exposing step of the first and second embodiments of the image forming method.
FIG. 6 is a sectional view schematically illustrating the developing step of the first and second embodiments of the image forming method.
FIG. 7 is a sectional view schematically illustrating the transferring step of the first embodiment of the image forming method.
FIG. 8 is a sectional view schematically illustrating the color image obtained by the repeating step of the first embodiment of the image forming method.
FIG. 9 is a sectional view schematically illustrating the laminating step of the third and fourth embodiments of the image forming method.
FIG. 10 is a sectional view schematically illustrating the exposing step of the third and fourth embodiments of the image forming method.
FIG. 11 is a sectional view schematically illustrating the developing step of the third and fourth embodiments of the image forming method.
FIG. 12 is a sectional view schematically illustrating the transferring step of the third embodiment of the image forming method.
DETAILED DESCRIPTION OF THE
INVENTION
First, preferred embodiments of the present invention are described below.
(1) The light-sensitive polymerizable layer preferably comprises a light-sensitive layer containing the silver halide and a polymerizable layer containing the ethyl
|
