JPH08110633A - Image forming method of printing paper - Google Patents

Abstract

PURPOSE: To provide a method capable of efficiently and cost effectively forming images directly on a plate having high accuracy. CONSTITUTION: This image forming method consists of a stage for forming the images by ink jet using opaque ink 47 on the ink repulsion layer 43 of the printing original plate 10 laminated with a base 40, a photosensitive resin layer 42 and the ink repulsion layer 43 in this order, a stage for exposing the photosensitive resin layer 42 by using active rays through the parts of the ink repulsion layer 43 not provided with the image formed by the ink jet and a stage for developing the printing original plate 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for an offset printing plate (PS plate) which is provided with its own photosensitivity in advance and which can form an accurate and highly precise image at low cost.

[0002]

2. Description of the Related Art Image forming technology for printing plates is currently undergoing a major revolution. Toray Co., Ltd. developed and introduced a very elaborate printing plate using photosensitive chemicals, silicone rubber, and other polymers with great success. The main patents for this type of printing plate are US Reissue Patent No. 30,670, US Patent Nos. 3,593,641 and 3,846,816.
No. 3,916,426, No. 3,983,75
No. 8, No. 4,128,326, No. 4,145,1
No. 35, No. 4,259, 905, No. 4,347,
There are specifications such as No. 303 and No. 4,378,423.

In Japanese Patent Laid-Open No. 63-153551, a cutout image is prepared from an opaque film, the cutout image is attached to a transparent plastic film having a thickness of 10 μm to 50 μm, and a photosensitive printing plate precursor is exposed. A method is disclosed. Next, the transparent film on which the image is attached is directly placed on a printing plate precursor composed of a plastic or aluminum substrate and a photosensitive polymer layer. This method has the advantage that it can replace the expensive optical transfer process using a chemical developer such as silver halide. To form an image on the printing plate precursor, press handwriting or transferred characters on the transparent film to create an original image, directly contact the image-formed photosensitive printing plate original plate, and irradiate the original image with actinic rays. The printing plate is exposed to light and an image is created.

The process of gluing cut-out images from an opaque film and applying characters is very time consuming and requires accuracy. In such a process, the cutout image attached to the film has a thickness of 10 μm to 50 μm.
There is a special restriction that it must be μm. When the thickness of the image is less than 10 μm, the strength of the film becomes insufficient in terms of manual work. If the thickness of the cut-out image exceeds 50 μm (depending on the thickness of the film), light will diffuse between the characters and the photosensitive resin layer, resulting in a deterioration of the quality of the image obtained on the printing plate.

Further, it is a difficult and basically impossible operation to accurately mount the transparent layer on which the image is attached on the printing plate precursor. For example, air pockets may be created between the transparent layer and the printing plate during manual work, causing a serious situation of light diffusion. at least,
Accurate placement of the image on the printing plate precursor often requires manual time for vacuum suction. Whether the characters are applied to the image-formed layer by adhesion or other methods, or by handwriting with a paint marker, etc., this method is inferior in reliability to the light transfer process by the silver salt method, Described in published patent applications. It is a well-known fact that this method suffices only if exact duplication does not have to be achieved and low cost achievement is the primary objective.

In Japanese Patent Laid-Open No. 63-153552, an upper surface of a photosensitive resin layer of a printing plate precursor is covered with an additional transparent plastic film having a thickness of 1 μm to 50 μm, and an image is formed on the photosensitive resin layer through an original drawing. A method of exposing for formation is disclosed. When the transparent plastic film of the printing plate precursor is brought into direct contact with the original image and then the photosensitive resin layer is irradiated with actinic rays, exposure for image formation can be carried out.
The original drawing uses a method of pressing handwritten transfer characters with a paint marker on the film, a method of printing using a word processor or computer by thermal transfer, impact printing, or pen printing (XY plotter), and using silver halide, etc. It can be manufactured by the original film positive obtained in the light transfer process. Since the printing plate is provided with a transparent plastic film, the original drawing can be easily removed before printing. Japanese Unexamined Patent Publication No. Sho 6
A similar process is also required in Japanese Patent Laid-Open No. 3-153551.

US Pat. No. 4,833 to Zerillo
No. 3,486 discloses a method for producing a lithographic printing plate using an inkjet printer.
In the method and apparatus described in this patent, an inkjet printer directly forms a hydrophobic image on an aluminum substrate of a lithographic printing plate. No photopolymer is used. The lithographic printing plate obtained as a result is placed on a lithographic printing machine, where the hydrophobic lithographic printing ink adheres only to the hydrophobic image formed by the inkjet printer. In the method disclosed in the Zerillo patent,
Although positive type printing plates can be manufactured, they cannot be used for image formation of negative type printing plates. This is because the hydrophobic ink has no effect when it is used to form an ink repelling area (non-image area) for developing a negative type printing plate.

Cameras, used as a means of forming images on film, have been used successfully to produce desired images, but are expensive and require considerable skill to produce accurate images. In light of these drawbacks, efforts have been made to invent a film-free plate manufacturing system that replaces the conventional technology by directly forming an image on a plate or manufacturing a printing plate without using a photographic film. It has been done. Experiments have also been conducted around plate direct image forming systems using laser image forming technology, but at present, these systems are mainly experimental ones, and have the precision required to be widely accepted in the market. In terms of points, we have not seen a solution yet.

Even more important is the advancement of current technology for plate resolution. Efforts are underway to improve the resolution of this type of system, as well as other systems, far beyond the currently achieved standard of about 300 dots / inch. In contrast, the minimum market-recognized resolution is at least 2
400 dots / inch or more.

Both wet offset plates and waterless planographic plates are well known in the art. FIG. 1 illustrates a waterless lithographic printing plate having a support 20, a photosensitive resin layer 21, and an ink repellent layer 22 typically made of a silicone rubber layer. In the waterless lithographic printing plate technique, an accurate recess is formed and filled with the ink 23. In the conventional wet offset plate seen in FIG. 2, a wet offset support 30 is provided and ink 31 and fountain solution 32 are used. As mentioned above, both waterless lithographic printing plates and wet offset plates have various shortcomings.

[0011]

If it is possible to economically produce high quality products by direct image formation on the plate, printers will be able to dramatically reduce labor costs, work speed and accuracy. , Can improve consistency. Expenses cannot be ignored, but they can be reduced. Therefore, this is an important object of the present invention.

A further object of the present invention is a novel method of direct image formation on a printing plate which is efficient, economical and highly precise, and can be used in such a method to print a large number of various kinds of images. It is to provide a novel plate and an efficient method capable of forming an accurate image on a printing plate. It is also an object of the present invention to provide a method of forming an image directly on a printing plate which allows the production of positive and negative type printing plates.

Many of the printing plates used today require the use of water, alcohol and chemicals for printing. As a result, serious environmental problems occur, printing costs rise, and the quality of printed matter deteriorates. Therefore, providing a novel waterless lithographic printing plate that is used to print many types of images is to use this printing plate without emulsifying ink or water and without using a camera or film. It is an object of the present invention, as well as a method by which an image can be made and printed on a high density, high contrast, high quality and more precise print.

Furthermore, it is an object of the present invention that it is easy to use and does not require any dampening water-related problems, no maintenance of the dampening water device is required, no alcohol is required and, as a result, it is suitable for printing start-up. It is also included to provide a method for forming an image on a printing plate, which is capable of reducing the amount of waste paper.

[0015]

The method for forming an image on a printing plate according to the present invention for achieving the above-mentioned object is provided with a support,
A step of inkjetting an image using an opaque ink on the ink repellent layer of a printing plate precursor laminated in the order of a photosensitive resin layer and an ink repellent layer, and the ink repellent layer on which the inkjetted image is not provided. Through the step of exposing the photosensitive resin layer with an actinic ray, and developing the printing plate precursor.

Another image forming method according to the present invention is
A support, a photosensitive resin layer, an ink-repellent layer and a transparent coating film are laminated in this order on the transparent coating film of the printing plate precursor, a step of inkjetting an image with an opaque ink, the inkjetted image is Exposing the photosensitive layer with actinic radiation through a portion of the transparent coating film not provided, removing the transparent coating film from above the ink repellent layer, and developing the printing plate precursor It is characterized by.

Still another image forming method according to the present invention is
A step of inkjetting an image with an opaque ink on the ink-repellent layer of a printing plate precursor laminated with a support, a photosensitive resin layer and an ink-repellent layer in this order, and the inkjet image is not provided. From the step of exposing the photosensitive resin layer using an actinic ray through the portion of the ink repellent layer, and the step of physically separating the unexposed portion of the ink repellent layer and the exposed portion of the ink repellent layer. It is characterized by becoming.

Further, according to still another image forming method of the present invention, an opaque film is formed on the transparent coating film of the printing plate precursor in which a support, a photosensitive resin layer, an ink repellent layer and a transparent coating film are laminated in this order. Inkjetting an image with an ink, exposing the photosensitive layer with actinic radiation through a portion of the transparent coated film on which the inkjetted image is not provided, and an unexposed portion of the ink repellent layer And a step of physically separating the exposed portion of the ink repellent layer from each other.

In the present invention, "ink" means a material forming a pattern by an ink jet method, and "ink" means a material forming an image on a printed matter. It has now been found that the disadvantages found in the prior art can be easily overcome by a new, inexpensive and precise new waterless lithographic plate with a photosensitive resin layer. This waterless planographic original plate comprises a substrate (generally plastic or aluminum), a photosensitive resin layer, and an ink repellent layer. A light-transmitting coating film may be optionally provided on the ink repellent layer of the printing plate precursor.

To form an image on the printing plate precursor, characters or images (hereinafter, both are collectively referred to as a picture) are provided on the coating film on the printing plate precursor or on the ink repellent layer. The pattern can be placed directly on the ink repellent layer, directly on any coating film, or at any position between the printing plate precursor and the source of actinic radiation. The picture is formed of a non-light transmissive material, preferably an opaque ink from a laser jet printer.

Inkjet technology can produce very high quality images from either scanned film or digital information. 3 inkjet printers
Images can be created with a resolution as high as 00 dots / inch.
High quality resolutions of 00 dots / inch or more are possible. A typical jet printer is Hewlett-Pa
Commercially available from manufacturers such as ckard, Epson, IBM, etc., and are US Pat. Nos. 5,245,365, 5,235,346, and 5,230,732. Typical models that can be used include Hewlett-Pack
There are models HP 12006 and HP 300XL from ard.

After the ink pattern is created, the printing plate precursor is exposed with an effective light source. The light beam exposed to the printing plate precursor reaches the photosensitive resin layer directly or through a transparent coating film provided as necessary. The photosensitive resin layer reacts by receiving a light ray, and the image of the obtained pattern is permanently stored in the printing plate precursor.

[0023]

EXAMPLES The usage of the ink jet system according to the present invention will be described in detail with reference to FIGS. 3 to 7 for a positive type original drawing film unnecessary printing plate and FIGS. 8 to 12 for a negative type original drawing film unnecessary printing plate. . Similarly, the positive type printing plate using the light transmissive coating film is shown in FIGS. 13 to 17, and the negative type printing plate using the light transmissive coating film is shown in FIGS.
2 is shown.

Now, returning to FIG. 3, the whole positive type printing plate precursor according to the present invention is designated by reference numeral 10. Reference numeral 40 denotes a support made of aluminum, plastic, or another appropriate material, and includes (optional) primer 41 coated with an ink repellent layer 43, and photosensitive resin layer 4
2 are provided. The ink repellent layer 43 may be any known material that repels printing ink, but a silicone rubber layer is suitable. As the photosensitive resin layer 42, a photoinsoluble photosensitive resin composition is usually used.

According to the image forming method of the present invention, an ink jet printer, which is shown as a large number of jet printers 45, is placed at an appropriate position to form a very accurate pattern of ink markings 46 on the silicone rubber layer 43. It is provided. It is easy and possible to program the jet printer 45 in a very well known manner electronically by means of a computer C in order to achieve a very fine and very precise resolution. The ink used in the jet printer 45 is known to be opaque to the specific form of actinic rays used later in the exposure process. For example, the ink 47 must be opaque to UV light if UV exposure is expected. Opaque ink marking 4 forming a desired pattern on the photosensitive resin layer 42
6 can be extremely thin, of course.

Next, referring to FIG. 4, by using the illustrated conventional ultraviolet light source 65, it is possible to easily form a photographic image on the prepared printing plate. The light ray L, preferably ultraviolet rays, passes through the silicone rubber layer 43 and penetrates to the photosensitive resin layer 42 except for the portion where the ink marking 46 is made by the jet printer 45. Photosensitive resin layer 42
Of the above, when the portion not covered with the ink marking 46 is exposed, the silicone rubber layer 43 becomes the photosensitive resin layer 4
It is firmly joined to 2.

In FIG. 5, the unexposed area of the silicone rubber layer 43 (previously under the ink marking 46) is
Basically, it shows a state of being softened by various well-known pretreatment solutions and developing solutions. When a development step consisting of one of several development methods that can be used is then carried out, the unexposed areas 60 of the silicone rubber layer 43 are conveniently removed and the silicone rubber layer 43 in the exposed areas 61 is removed.
Remains, and the exposed region 5 of the photosensitive resin layer 42 is left by photo-curing.
It is joined to 4. Since the silicone rubber layer of the present invention is not photo-reactive, it has already been sufficiently cured and has low surface tackiness. Therefore, the ink marking 46 can be easily removed by the pretreatment liquid or the developing liquid.

FIG. 6 shows the processed positive printing plate. In this figure, the silicone rubber layer 4
The non-image area 50 remaining as the exposure area 61 of No. 3 is an ink repulsion portion. Unexposed portion 53 of photosensitive resin layer 42
The image area 51 above is the ink receiving portion. The non-image area 50 exposed to ultraviolet rays is bonded to the non-exposed area 54 of the photosensitive resin layer 42, and even after the unexposed area 60 of the silicone rubber layer 43 is removed as described with reference to FIG. The non-image area 50 remains. By using the above-mentioned elaborate inkjet technology, the sharpness, fidelity and quality of the non-image area 50 are improved at once. Further, since the ink is directly applied onto the printing plate precursor, there is no problem of light diffusion. Further, in the developing operation with the pretreatment liquid or the developing liquid, only the exposed portion 53 of the photosensitive resin layer can be colored by using the coloring agent, and the plate inspection property of the obtained printing plate can be improved.

FIG. 7 is a diagram showing a typical printing procedure using the printing plate produced according to the present invention. The original unexposed area 60 is filled with the ink 23 in the image area 51 from which the silicone rubber layer 43 has been removed. As described above, the non-image area 50 is an ink repelling area of the silicone rubber layer. 8 through 12 with reference numerals labeled'to indicate like elements as in FIGS. 3 through 7.
Figure 3 illustrates the steps taken in a negative type treatment as opposed to the positive type of Figures 3-7. As the photosensitive resin layer, a photosolubilizing photosensitive resin composition is usually used. Photosensitive resin layer 4 by the light from the light source 65 '
When 2 ′ was exposed (FIG. 9), the positive type treatment strengthened the bond by exposure, whereas the exposed portion 5
4 ', the photosensitive resin layer 42' and the silicone rubber layer 4
The bond between the 3 ′ is weakened (FIG. 10).

The photosensitive resin layer 42 'of the unexposed portion 53'
(FIG. 10) is the unexposed region 6 of the silicone rubber layer 43 '.
When joined to 0 ', a non-image area 50' is formed (FIG. 11). On the other hand, the silicone rubber layer 43 'in the exposed area 61' is removed in the developing process. As shown in FIG. 11, the non-image area 50 'is an ink repelling portion, and an ink receiving portion 51' is also provided. In the negative type processing of FIGS. 8 to 12, the image area 51 ′ is located on the exposed portion 54 ′ of the photosensitive resin layer 42 ′. Printing is performed as shown in FIG.

Turning now to FIG. 13, a positive-type printing plate using the transparent coating film according to the present invention is generally designated by the reference numeral 100. Reference numeral 70 is a support made of aluminum, plastic or other suitable material, on which an (optional) primer 71 coated with an ink repellent layer 73 and a photosensitive resin layer 72 are provided. . The ink repellent layer 73 may be any known material that repels printing inks, for example a silicone rubber layer is suitable. Reference numeral 74 is a novel transparent coating film used in the present invention. As the photosensitive resin layer, a photoinsoluble photosensitive resin composition is usually used.

Unlike the conventional printing plate, the transparent coating film 74 is used as a part of the printing plate original plate, and before the image characters are placed, the printing plate original plate 100 is manufactured at the time of manufacturing the printing plate original plate 100 or the like. Provided on top of. In a conventional printing plate, a pattern is formed on a film, and then the film on which the pattern is formed is attached to the printing plate. By preparing the printing plate precursor 100 including the transparent coating film 74 as a part,
There is no need for a disposing step required for adhering the image-formed transparent film to the printing plate precursor, that is, time for vacuum suction or the like. As described above, a conventional printing plate or a conventional image forming method in which after the image is formed on the film, the image-bearing film is applied to the photosensitive resin layer or the ink repellent layer (or the covering sheet on these) On the other hand, the printing plate precursor 100 is obviously advantageous.

In the image forming method of the present invention, the ink jet printer shown as a large number of jet printers 75 in FIG. 13 is provided at a position suitable for forming an accurate pattern of the ink marking 76 on the transparent coating film 74. ing. In a manner known per se, it is easy and possible to program the jet printer 75 using the computer C to achieve a very fine and very precise resolution. The thickness of the film 74 may be any suitable thickness, and it is already applied to the printing plate precursor 100 in a plain state prior to image formation by the jet printer 75.

The jet printer 75 uses an ink which is known to be opaque to the particular form of actinic radiation used later in the exposure process. For example, if the UV exposure is intended, the ink 77 should be opaque to the UV. Film 7
The impermeable ink markings 76 forming the desired pattern on the surface 4 can of course be made very thin.

Next, as shown in FIG. 14, if a conventional light source 95 such as ultraviolet rays is used, a photographic image can be easily formed on the prepared printing plate precursor. Ultraviolet rays are suitable for the light ray L, but the covering film 74 is excluded except for the portion where the ink marking 76 is applied by the jet printer 75.
Through and through the silicone rubber layer 73 to reach the photosensitive resin layer 72. When exposure is performed through a portion of the covering film on which the ink marking 76 is not applied,
The silicone rubber layer 73 is firmly bonded to the photosensitive resin layer 72.

After exposure, the covering film 74 and the ink jet printed pattern are removed from the silicone rubber layer 73 and may simply be discarded or used as a reference or stored for recycling. it can.
FIG. 15 is a diagram showing a state in which the unexposed region 90 (the portion below the ink marking 76) of the silicone rubber layer 73 is softened by various well-known pretreatment solutions and developers. . The silicone rubber layer in the unexposed areas 90 is conveniently removed in a developing step which may be any of a number of developing methods. The silicone rubber layer in the exposed area 91 remains and is bonded to the exposed area 84 of the photosensitive resin layer 72 by curing. Since the silicone rubber layer of the present invention is not photoreactive, it has been sufficiently cured and has low surface tackiness. Therefore, the ink marking 46 can be easily removed by the pretreatment liquid or the developing liquid.

FIG. 16 shows a positive type development-processed printing plate, in which a silicone rubber layer 73 is shown.
The non-image area 80, which is the exposed area 91, is the ink repelling portion. The image area 81 in the unexposed portion 83 of the photosensitive resin layer 72 is an ink receiving portion. The non-image area 80 exposed by the ultraviolet rays L is bonded to the unexposed portion 84 of the photosensitive resin layer 72, and the silicone rubber layer 7 is shown in FIG.
This non-image area 80 remains even after the third unexposed area 90 is removed. As described above, the sharpness, fidelity, and quality of the non-image area 80 are improved all at once by using the sophisticated inkjet technology. Further, since the transparent layer already arranged on the printing plate precursor is coated with ink, there is no problem of light diffusion. Further, in the developing operation with the pretreatment liquid or the developing liquid, by using the coloring agent, only the exposed portion 83 of the photosensitive resin layer can be colored, and the plate inspection property of the obtained printing plate can be improved.

FIG. 17 is a diagram showing a typical printing procedure using the printing plate manufactured according to the present invention. Ink 2
3 is applied to the removed image area 81 of the silicone rubber layer 73, which was originally the unexposed area 90. As described above, the non-image area 80 has the silicone rubber layer 7
3 is the ink repulsion area. 18 to 22, the reference numbers are marked with a'to indicate that they are similar to the elements of FIGS. 13 to 17, but in these figures, FIG.
3 to 17 illustrate the steps involved in processing negative types as opposed to positive types. When exposed through the covering film 74 'from the light source 95' (FIG. 19), the bond between the photosensitive resin layer 72 'and the silicone rubber layer 73' is weakened in the exposed portion 84 '(FIG. 20). .

The photosensitive resin layer 7 in the unexposed portion 83 '
2'is joined to the unexposed area 90 'of the silicone rubber layer 73' to form a non-image area 80 ', while the silicone rubber layer 73' in the exposed area 91 '(FIG. 20).
Are removed in the developing process. As can be seen from FIG. 21,
A non-image area 80 'which is an ink repelling portion and an image area 81' which is an ink receiving portion are provided. Image area 8
1'is located on the unexposed portion 84 'of the photosensitive resin layer 72'. As already explained in detail, printing is carried out by the method shown in FIG. Here, as the photosensitive resin layer, a photosolubilizing photosensitive resin composition is usually used.

It is obvious that the image formation of the prepared printing plate precursor can be carried out by the present invention by using any one of ordinary ultraviolet rays and several kinds of light sources. The image is formed on the printing plate precursor directly on the silicone layer 43 or prior to the image formation.
No. 4, since the image-formed film is formed on the printing plate precursor, no special work is required. The time and expense spent for a vacuum suction system, and the complications used in previous methods to deposit the imaged film on the printing plate precursor are eliminated. Also,
The problem of light refraction is reduced and the sharpness, clarity and quality of the printing plate are improved.

The image is preferably formed directly by an inkjet printer which uses an impermeable or light absorbing ink. In such a method, the image is stored in the computer that operates the inkjet printer, so that the image is easily formed and accurate reproduction is possible. When exposed to light, the image with the impermeable ink acts as an effective mask for certain areas of the printing plate, blocking the exposure to UV light, thus allowing photocuring or photocuring of the photosensitive resin layer. Allows solubilization to form an image on the printing plate. Since vacuum suction is not necessary, it is even possible to incorporate a light source into the inkjet system so that the printing plate can be imaged and exposed in one step.

When used with a computer-programmed printing system (inkjet, thermal printer, etc.), multiple images can be formed directly from digital files. In this way, it is possible to easily form an image on a set of four-color printing plates in a short time without using a film or other mechanical artwork. In a multicolor copying system, paper is mounted on a rotating drum and color inks having different colors such as black, cyan, magenta, and yellow dyes are applied. The resulting image is
The original is represented in four colors. With this system, it is possible to use the same equipment to create proofs for inkjet printers for confirmation. Both proofs and printing plates can be created using the same system, making color matching easy and convenient.

In producing a four-color printing plate, after confirming the final color of the paper, the unexposed printing plate precursor is placed on the drum. An image representing a single color of the four colors is formed on the surface of the printing plate precursor, and the printing plate developed as described above is obtained.
This process is repeated for the other three color images, such as placing a new plate on the drum to form the remaining image for each dye on the plate. In this way, a set of four masked plates, each representing each element of the four color image, can be produced.

Thus, a cover sheet either directly on the photosensitive resin or integrated with the surface of the printing plate, in combination with an inkjet system directed to create the desired (computerized) pattern with an impermeable ink. It will be appreciated that the image forming system according to the present invention has unique advantages in that the image is formed on the image.

Although this disclosure generally describes the use of one form or the like of silicone rubber as the ink repellent layer, various alternatives that are resistant to ink can be used. There is no intent to limit the scope of the invention to the use of silicone rubber as many other materials known in the art can be used instead as ink repellent layers. Further, the printing plate in which the photosensitive resin layer in the portion where the ink repellent layer is peeled off remains up to this point, but the photosensitive resin layer is dissolved or peeled by the developing operation to expose the support or the primer layer. It can also be applied to a method of manufacturing a type of printing plate.

The novel features of the present invention are equally applicable to positive-type and negative-type systems, can be used for black and white reproduction, and can be used with virtually any combination of colors. Further, the imaging method of this invention can be used in both wet offset and dry printing systems. Other modifications and variations are possible within the spirit and scope of the invention as claimed, as will be apparent to those skilled in the art.

[0047]

According to the above-mentioned image forming method of the present invention, since an image is formed on a printing plate, no film is required, and an accurate and highly precise image can be formed at low cost. Also, those that use water or aqueous solution in the printing process,
It can be applied to various kinds of photosensitive printing plate products.

Further, since a waterless planographic printing plate is used as the printing plate, it is convenient because the offset printer can perform printing without dampening water. In this way, the waterless lithographic printing plate does not require water or alcohol and does not pollute the printing chamber, which has been required in the conventional wet offset printing plates, and it enables high quality printing to be achieved by simple printing work. It can be done with productivity.

Further, according to the present invention, exposure and development can be easily carried out by a manual work or an automatic processing machine. In addition to the wet printing or the dry printing, this printing can be used with a normal offset printing machine, and a wide variety of inks can be used.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a conventional waterless planographic printing plate.

FIG. 2 is a schematic view of a conventional wet offset plate.

FIG. 3 is a cross-sectional view of an inkjet process for forming a positive type printing plate precursor according to an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing an exposure process for a printing plate precursor without a film according to the present invention.

FIG. 5 is a schematic cross-sectional view showing an arbitrary form of pretreatment or development and the procedure of development according to the present invention.

FIG. 6 is a diagram showing a state of a printing plate after development in one example according to the method of the present invention.

FIG. 7 illustrates an exemplary printing method using a printing plate embodying features of the present invention.

FIG. 8 is a cross-sectional view corresponding to FIG. 3 of a method of using a negative type printing plate precursor according to the present invention.

9 is a sectional view of the negative type printing plate precursor corresponding to FIG. 4. FIG.

FIG. 10 is a sectional view of the negative type printing plate original plate corresponding to FIG. 5;

FIG. 11 is a sectional view of the negative type printing plate precursor corresponding to FIG. 6.

FIG. 12 is a sectional view of the negative type printing plate precursor corresponding to FIG. 7.

FIG. 13 is a cross-sectional view of a positive type printing plate precursor which is an embodiment of the present invention before being processed.

FIG. 14 is a schematic cross-sectional view showing an exposure process through a coating film according to the present invention.

FIG. 15 is a schematic sectional view showing an arbitrary form of pretreatment and a developing procedure according to the present invention.

FIG. 16 is a diagram showing a processed state of an embodiment of a printing plate according to the method of the present invention.

FIG. 17 illustrates a typical printing method using a printing plate embodying features of the present invention.

FIG. 18 is a cross-sectional view corresponding to FIG. 13 of a method of using a negative type printing plate precursor according to the present invention.

FIG. 19 is a sectional view of the negative type printing plate original plate corresponding to FIG. 14;

FIG. 20 is a cross-sectional view of the negative type printing plate precursor corresponding to FIG. 15.

FIG. 21 is a sectional view of the negative type printing plate precursor corresponding to FIG. 16.

FIG. 22 is a sectional view of the negative type printing plate original plate corresponding to FIG. 17;

[Explanation of symbols]

 10 printing plate original plate 40 support 41 primer layer 42, 42 'photosensitive resin layer 43, 43' ink repulsion layer (silicone rubber layer) 45 jet printer 47 ink 54, 54 'exposed portion 60, 60' unexposed area 61, 61 'Exposed area 74 Transparent coating film

Claims (8)

[Claims] 1. A step of ink-jetting an image using an opaque ink on the ink-repellent layer of a printing plate precursor, in which a support, a photosensitive resin layer and an ink-repellent layer are laminated in this order. An image forming method for a printing plate, comprising the steps of exposing the photosensitive resin layer with an actinic ray through a portion of the ink repellent layer not provided with, and developing the printing plate precursor. 2. A step of inkjetting an image using an opaque ink on the transparent covering film of a printing plate precursor, in which a support, a photosensitive resin layer, an ink repellent layer and a transparent covering film are laminated in this order, The step of exposing the photosensitive layer with actinic rays through the portion of the transparent coating film on which the inkjet image is not provided, the step of removing the transparent coating film from above the ink repellent layer, and developing the printing plate precursor. A method for forming an image on a printing plate, which comprises the steps of: 3. A step of ink-jetting an image using an opaque ink on the ink-repellent layer of a printing plate precursor, in which a support, a photosensitive resin layer and an ink-repellent layer are laminated in this order. The step of exposing the photosensitive resin layer with an actinic ray through the part of the ink repellent layer where is not provided, and the part of the ink repellent layer which is not exposed and the part of the exposed ink repellent layer are physically A method for forming an image on a printing plate, which comprises a step of separating into two. 4. A step of inkjetting an image using an opaque ink on the transparent covering film of a printing plate precursor in which a support, a photosensitive resin layer, an ink repellent layer and a transparent covering film are laminated in this order, Exposing the photosensitive layer with actinic radiation through a portion of the transparent coated film not provided with the inkjet image, and a portion of the unexposed ink repellent layer and a portion of the exposed ink repellent layer. A method for forming an image on a printing plate, which comprises the step of physically separating the 5. The method of forming an image on a printing plate according to claim 1, wherein the ink repellent layer is a silicone rubber layer. 6. The image forming method for a printing plate according to claim 1, wherein the photosensitive resin layer is a photoinsolubilizing photosensitive resin composition. 7. The method for forming an image on a printing plate according to claim 1, wherein the photosensitive resin layer is a photosolubilizing photosensitive resin composition. 8. The method of forming an image on a printing plate according to claim 1, wherein ultraviolet rays are used as actinic rays, and the jetted ink is opaque to the ultraviolet rays.