JPH0976657A - Manufacture of direct lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a direct lithographic printing plate which makes it possible to obtain a printed matter of high quality without unnecessary toner stuck to a background part and without lack of a printing element part when the printing element part is formed by an electrophotographic method. SOLUTION: This method for manufacturing a direct lithographic printing plate has the steps of sticking toner onto an image receptive layer to form a printing element part by an electrophotographic method, and then hydrophilizing the part except the element part of the layer by etching, and comprises the step of removing the one stuck to the surface of the layer except the element part by cleaning the solution swelled only at the resin contained in the layer without stepping the resin contained in the toner on the surface of the layer formed with the element part before etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-quality direct drawing type lithographic printing method in which unnecessary toner is not attached to a portion other than an image area on an image receiving layer, particularly in an electrophotographic method using a dry toner. It relates to a method of manufacturing a plate.

[0002]

2. Description of the Related Art In recent years, with the progress of computer equipment,
Even in the light printing industry, PPC (plain pa) using dry toner is excellent in terms of plate making speed and plate making cost.
per copier) A so-called CTP (Computer ToP) that directly outputs to a plate material using a copier or a laser beam printer and forms an image by electrophotography.
late) has become popular.

Such a direct drawing type lithographic printing plate is generally produced as follows. First, formed on the original plate,
An image area is formed by adsorbing a lipophilic toner on the surface of the image receiving layer composed of a binder and an inorganic pigment such as zinc oxide. After the image area is formed, the portion of the surface of the image receiving layer other than the image area (hereinafter referred to as the background area) is hydrophilized by a treatment (desensitizing treatment) with an etching solution containing potassium ferrocyanide, phytic acid, or the like. As a result, a printing plate having a hydrophilic background portion and a lipophilic toner image portion can be obtained and used for offset printing. However, when the image area is formed using a printer that uses an electrophotographic method such as a laser beam printer, fine unnecessary toner that cannot be visually identified is attached to the background area. When printing is performed using a printing plate on which unnecessary toner adheres, the unnecessary toner also accepts ink, which causes a background stain that is a practical problem on the printed matter.

The cause of the toner adhering to the background portion is
It is conceivable that unnecessary toner on the electrostatic drum or fine toner floating in the hardware adheres to the image receiving layer. However, in any case, it is the current situation that it is very difficult to remove the unnecessary toner inside the hardware. On the other hand, studies have been made to eliminate toner stains by improving printing plate materials, and various studies have been made, but none of them are sufficient.

Further, in Japanese Patent Laid-Open No. 41-320844, a printing plate material is formed on a printing plate material with a toner, desensitized with an etching solution, and then a printing plate material is prepared with a special emulsion type mixture. A method of removing toner stains on the background by treating the surface is disclosed. Since the special mixture is a solvent that dissolves or swells the resin used in the toner, not only the toner stain on the background portion but also the toner forming the image area is easily removed. The method disclosed in the above publication has a drawback that it is difficult to control so as to remove only the unnecessary toner in the background portion, and chipping of the image area easily occurs.

[0006]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above-mentioned drawbacks, and an object thereof is an unnecessary toner attached to a background portion when an image portion is formed by an electrophotographic method. It is an object of the present invention to provide a method for producing a high-quality direct-drawing type lithographic printing plate which is free from defects and has no image area defect.

[0007]

Means for Solving the Problems As a result of intensive studies, the inventors have found that after forming an image area on an image receiving layer and before performing an etching process, the resin contained in the toner is not dissolved and the image receiving layer is not dissolved. It was found that by treating the surface of the image-receiving layer with a cleaning solution having the function of swelling the layer, the background stain is significantly reduced, and also the chipping of the image area due to cleaning can be prevented, and the present invention is completed. I arrived. That is, in the present invention, a toner is attached to the image receiving layer by electrophotography to form an image area, and then a portion other than the image area of the image receiving layer is made hydrophilic by an etching treatment to produce a lithographic printing plate. In the method, before the etching treatment, the surface of the image receiving layer on which the image area is formed is washed with a cleaning solution which does not substantially swell the resin contained in the toner but only the resin contained in the image receiving layer. The toner adhering to the surface of the image receiving layer other than the image area is removed.

The cleaning solution is preferably a solution containing a glycol ether compound that does not substantially dissolve the resin contained in the toner.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. FIG. 1 is a cross-sectional view showing a state in which an image area is formed on a generally used original plate. The original plate is formed by forming an image receiving layer 2 on a water resistant support 1. The image receiving layer 2
Toner is attached to the upper portion of the image area 3 by electrophotography.
Are formed. Unwanted toner 4 is also attached to the background portion on the image receiving layer 3, which causes a background stain on the printed matter.

The image receiving layer 2 comprises a binder made of resin, an inorganic pigment and the like. As the binder, a resin capable of fixing an inorganic pigment and having an appropriate water resistance is used, and specifically, a polyester resin, an epoxy resin, a urethane resin, an acrylic resin or the like can be mentioned, preferably A solvent-type acrylic resin or the like whose hydrophilicity and lipophilicity can be easily controlled is used. Examples of the inorganic pigment include zinc oxide, clay, talc, silica and the like.

The water resistant support 1 is not particularly limited and is formed of polyester, polypropylene, polyethylene or the like. Preferably, a polyester support which is excellent in mechanical strength and dimensional stability and is not affected by moisture is used. More preferably, a polyester void-containing biaxially stretched film (Toyobo Crisper, manufactured by Toyobo Co., Ltd.) having excellent cushioning properties and bending properties is used.

The toner forming the image area 3 is made of resin, ferrite, carbon or the like. Examples of the resin contained in the toner include resins having a Tg of room temperature or higher and softening at 80 ° C. to 150 ° C., and specific examples thereof include styrene resin, acrylic resin, epoxy resin, polyester resin and the like. However, a styrene-acrylic copolymer is preferably used.

In the method for producing a printing plate of the present invention, after the image area 3 is formed as described above, the surface of the image receiving layer 2 is not swelled with the resin contained in the toner and the image receiving layer 2 is formed.
Then, a step of removing the toner adhering to the surface of the image receiving layer 2 other than the image area 3 is carried out by treating with a cleaning solution having a function of swelling only the resin contained in.

In the cleaning solution used in the present invention, when the surface of the image receiving layer 2 is wet with the solution, the resin contained in the toner is not substantially swollen, and only the resin contained in the image receiving layer 2 is used. Any solution that swells and is softened may be used.

The fact that the resin contained in the toner does not substantially swell means that the resin contained in the toner does not soften so as to become tacky, that is, the toner is fixed on a film made of polyester or the like. When the solution is placed on the toner and wetted and then the wetted portion is rubbed, the toner does not spread and a linear tail is not drawn on the film.

Further, the resin contained in the image receiving layer is swelled, which means that when the surface of the image processing layer is wet with a solution and the wet portion is rubbed with a cotton swab, the resin is removed so that the resin falls off. The softened state. If even the resin contained in the toner swells and the toner particles become tacky, there arises a problem that unnecessary toner particles once removed are redeposited on the surface of the original plate.

Such a cleaning solution is appropriately selected depending on the resin contained in the image receiving layer 2 and the resin contained in the toner.

For example, as the resin contained in the image receiving layer 2, polyester resin, epoxy resin, urethane resin is used, and as the resin contained in the toner, styrene resin, acrylic resin, epoxy resin, polyester resin,
Preferably, when a styrene-acrylic copolymer is used, a glycol ether compound that does not substantially swell the resin contained in the toner is preferably used as the cleaning solution. Examples of such compounds include triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, and 3-methyl-3-methoxybutanol. These compounds may be used alone or in combination of two or more kinds, or may be appropriately mixed and used with water or the like. Further, for example, a hydrocarbon solvent such as toluene or xylene can be blended, but the blending amount is preferably less than 5% by weight. If it is 5% by weight or more, the resin contained in the toner may swell.

However, among the glycol ether type compounds, the compound in which the resin contained in the toner swells to such an extent that it becomes tacky cannot be used as a cleaning solution. As such a compound, for example, when the resin contained in the toner is a styrene resin, an acrylic resin, an epoxy resin, or a polyester resin, hydrogen at both ends of a molecule such as triethylene glycol dimethyl ether or diethylene glycol dibutyl ether is an alkyl group. A glycol ether-based compound substituted with is mentioned. Such a compound may swell and further dissolve the resin contained in the toner.

By wetting the surface of the image receiving layer 2 with the cleaning solution, substantially only the resin contained in the image receiving layer 2 can be swollen. At this time, the unnecessary toner 4a around the image area 3 and the image receiving layer 2 immediately below the toner 4 in the background area also swell around the edge of the image area due to the side etching effect. The unnecessary toner 4 shown in FIG. 1 is such that several toner particles are weakly adhered to the image receiving layer 2 in a state where the particle prototype is retained. On the other hand, in the image area 3, many toner particles are fused and fused to the image receiving layer 2 in a fused state. At this time, the side etching effect also acts on the image area 3, but since many toner particles are firmly fused to each other,
The influence on the image receiving layer 2 therebelow is extremely small as compared with the portion where the image area 3 is not formed.

The resin contained in the image receiving layer 2 and the resin contained in the toner are as described above, and when the suitable glycol ether compound is used as a cleaning solution, the surface of the image receiving layer 2 is By wetting with the cleaning solution, the resin contained in the image receiving layer 2 can be swollen to the extent that unnecessary toner can be removed. Then, when the resin contained in the image receiving layer 2 is swollen in this way, a physical external force such as brushing with a brush made of nylon, polypropylene or the like is applied to the image receiving layer 2 together with the swollen portion. The unnecessary toners 4 and 4a can be easily removed. The image resin layer 2 is removed until the support 1 is not exposed.

The method of wetting the image receiving layer 2 with the cleaning solution is not particularly limited, and examples thereof include coating, spraying, dipping and the like. Coating is preferred. Wet time is
The time is set so that the swelling action does not reach the image receiving layer 2 below the image area 3, and is determined in consideration of the type of binder included in the image receiving layer, and is usually 5 to 30 seconds. If left for a long time while being wet with the cleaning solution, the side etching effect may be excessively advanced, and the image area 3 may be chipped. After contacting with the cleaning solution for a predetermined time, the surface of the image receiving layer 2 is immediately contacted with water to dilute the cleaning solution,
The swelling of the image receiving layer 2 is stopped.

After the washing step, the original plate is desensitized by a conventional method such as a treatment with an etching solution containing potassium ferrocyanide, phytic acid or the like, so that the portions other than the image area 3 are hydrophilized. Printed version.

[0024]

EXAMPLES Examples will be shown below. In the examples, all parts mean parts by weight. The evaluation used in this example was performed based on the following methods.

1) Toner stain on the background portion A TEXEL ARO1 type offset printing machine manufactured by Shinano Kenshi Co., Ltd. was used to print on 3000 sheets of coated paper using the prepared printing plate, and the printed matter was judged as follows. The number of toner stains having a diameter of 20 μm or more per 1 mm ² of the background of the printing plate and the printed matter was measured using a magnifying glass of 15 times, and evaluated as ◯: less than 5 Δ: 5 to 10 ×: 11 or more .

2) Defect of image area Printed in the same manner as 1), and judged as follows. ◯: No chipping is observed even when observed with a 15 × magnifying glass. Δ: Some chipping is observed when observed with a 15 × magnifying glass, but cannot be visually discerned. X: A chip is clearly visible.

Example 1 A printing plate was prepared using the following materials. Original plate: Toyoplate DL (trade name, manufactured by Toyobo Co., Ltd.) (Water resistant support: polyester film, binder resin included in image receiving layer: acrylic resin) Toner: styrene-acrylic copolymer, ferrite, carbon Cleaning solution containing: Propylene glycol monoethyl ether 50 parts Triethylene glycol monobutyl ether 50 parts Etching solution: Phytic acid type etching solution (PP Clean H Wetty, product name, manufactured by Nikken Chemical Laboratory) Laser beam printer 1 (Canon laser shot B406D) was used to form an image area on the image receiving layer of the original plate. Wet the plate with the background cleaning solution,
After leaving it for about 10 seconds, the liquid was lightly absorbed by a sponge roller and rubbed 20 times with a nylon brush in water. Then, it was air-dried and the printing plate was wiped with cotton wool impregnated with an etching solution to prepare a printing plate.

Using this printing plate, 3000 sheets of coated paper were printed by the above printing machine (Fanson 10850 black was used as the ink, and a solution obtained by diluting the above etching solution with water 30 times was used as the dampening solution). The results of the above evaluations of the obtained printing plate and printed matter are shown in Table 1 for the printing plate and Table 2 for the printed matter. The same evaluation was performed in Examples 2 to 4 and Comparative Examples 1 to 3 described later, and the results are shown in Tables 1 and 2.

Example 2 A printing plate was prepared in the same manner as in Example 1 except that a solution having the following composition was used as a cleaning solution to obtain a printed matter. Propylene glycol monomethyl ether 30 parts Triethylene glycol monobutyl ether 70 parts

Example 3 A printing plate was prepared in the same manner as in Example 1 except that a solution having the following composition was used as a cleaning solution to obtain a printed matter. 3-methyl-3-methoxybutanol 100 parts

Example 4 A printing plate was prepared in the same manner as in Example 1 except that a solution having the following composition was used as a cleaning solution to obtain a printed matter. Dipropylene glycol monomethyl ether 80 parts Water 20 parts

Comparative Example 1 A solution having the following composition was used as a cleaning solution, and Example 1 was used.
A printing plate was prepared in the same manner as above to obtain a printed matter. Aromatic hydrocarbon solvent [Swazol 1800, trade name, manufactured by Maruzen Petroleum Co., Ltd.] 5 parts Triethylene glycol monobutyl ether 95 parts

COMPARATIVE EXAMPLE 2 A solution having the following composition was used as a cleaning solution, and Example 1 was used.
A printing plate was prepared in the same manner as above to obtain a printed matter. Propylene glycol 100 parts

Comparative Example 3 A solution having the following composition was used as a cleaning solution, and Example 1 was used.
A printing plate was prepared in the same manner as above to obtain a printed matter. Aromatic hydrocarbon solvent [Solvesso 100, trade name, manufactured by Esso Kagaku Co., Ltd.] 10 parts Water 60 parts Triethylene glycol monobutyl ether 25 parts Emulgen 913 [trade name, manufactured by Kao Corporation, surfactant] 5 parts

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

According to the method for producing a direct drawing type lithographic printing plate of the present invention, it is possible to obtain a high quality printing plate having no background toner stain. The method for producing a printing plate of the present invention is extremely useful for future development of digital printing for light printing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state where an image area is formed on an image receiving layer of an original plate.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Toshitake Suzuki 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory

Claims (3)

[Claims] 1. A lithographic printing plate is manufactured by applying a toner onto an image receiving layer by an electrophotographic method to form an image area, and then hydrophilizing a portion other than the image area of the image receiving layer by an etching treatment. In the method, before the etching treatment, the surface of the image receiving layer on which the image area is formed is washed with a cleaning solution that does not substantially swell the resin contained in the toner but only the resin contained in the image receiving layer. A method for producing a direct drawing type lithographic printing plate, characterized in that the toner adhering to the surface of the image receiving layer other than the image area is removed. 2. The method for producing a direct drawing type lithographic printing plate as claimed in claim 1, wherein the cleaning solution contains a glycol ether compound that does not substantially swell the resin contained in the toner. 3. The cleaning solution is triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, 3-
The method for producing a direct drawing type lithographic printing plate according to claim 2, which comprises at least one glycol ether compound selected from the group consisting of methyl-3-methoxybutanol.