JPH1058640A - Printing plate and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing plate which can write original information on a plate cylinder without intermediary of a film, reduce a plate making cost, shorten and facilitate a plate making operation and a method for manufacturing it. SOLUTION: The printing plate is manufactured by the steps of forming a silicate film on a chromium plating layer executed on a surface of a base material, coating the surface of the film with aniline and a potassium chloride water solution, energizing it with the plating layer side as a positive electrode and the water solution side as a negative electrode, electrolytically polymerizing it, and then removing the residual water solution, thereby forming a printing element portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a writable and erasable printing plate applied to a plate cylinder of an offset printing press and a method of manufacturing the printing plate.

[0002]

In an offset printing press, a PS plate has conventionally been used as a plate material utilizing the repulsion of ink and dampening water. This PS version is
An ultraviolet curable resin is formed in a pattern area where ink adheres, and an anodized aluminum is formed in a pattern pattern in a non-image area where dampening water adheres. And
Each time a printed document such as a character or picture changes, the PS plate is remade and wrapped around a plate cylinder of a printing press to perform printing.

In the production of the above-mentioned conventional PS plate, a printed document is color-separated using a color scanner to produce a silver halide film decomposed into halftone dots of four colors. Then, this film is brought into close contact with a raw plate formed by thinly applying a photosensitive resin on aluminum that has been entirely anodized, and by irradiating ultraviolet rays, the resin in the portion irradiated with the light rays is cured. The uncured portion of the resin is washed away with a developer.
This operation is performed using the above-mentioned four films to produce a printing plate of four colors (eye, veneer, yellow, and black).

However, in recent years, digitization of character and image information has been rapidly progressing, and plate making is performed in a short time on a plate cylinder of a printing press directly from a digital information collected on a computer without using a film. The demand for adopting a manufacturing method is increasing. Particularly, in small lot printing (the number of prints in one plate making is about 500 to 10,000 copies), such a request is extremely large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing plate and a method for manufacturing the same, which enable writing of document information on a plate cylinder without the use of a film, thereby reducing plate making costs and shortening and facilitating plate making operations. Is to do.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and a first invention is a printing plate which is wound around a plate cylinder of a printing press to perform printing. A printing plate comprising a silicate film formed on a chromium plating layer and an erasable aniline / polymer film formed on an image area on the surface of the silicate film.

The second invention relates to the method of manufacturing a printing plate, wherein a silicate film is formed on a chromium plating layer provided on the surface of the substrate, and aniline and an aqueous solution of potassium chloride are coated on the surface of the silicate film. The method is characterized in that an electrolytic polymerization is carried out by applying a current, using the chromium plating layer side as a positive electrode and the aqueous solution side as a negative electrode, and then performing electrolytic polymerization, and then removing the remaining aqueous solution to form an image portion.

According to a third aspect of the present invention, in addition to the method of the second aspect, an electrolytic solution is applied to the surface of the printing plate after forming the image area, the chromium plating layer is formed as a negative electrode, and the image area is formed as a positive electrode. To dissolve and remove the image area.

Further, the method for producing a printing plate according to the second and third aspects of the present invention specifically includes the following procedure.

(1) After chromium plating is applied to the surface of a substrate made of a stainless steel plate or the like, about 1 μm
A silicate film of m is formed by an electrodeposition method, and a plate material as a non-image area material is wound around a plate cylinder.

(2) An aqueous solution of aniline and potassium chloride is applied to the plate material made of the non-image area material, and then the plate material is used as a positive electrode, and the aqueous solution side is used as a negative electrode. Voltage several volts x several milliamps x 5-10
(Application of millisecond), a polymer film of aniline is formed on the surface of the positive electrode, and this is used as an image portion material.

The DC voltage is applied by placing a roller electrode made of a photoelectric conversion material (for example, amorphous silicon) which generates an electromotive force when irradiating a semiconductor laser beam, facing the plate cylinder via an aqueous solution film. Do.

(3) In order to erase the image portion formed as described above, the plate material is used as a negative electrode and the image portion is used as a positive electrode, aniline is changed to a reduced state, and its solubility in water is increased to remove it.

The silicate film formed by the electrodeposition method as described above is a hydrophilic surface having a contact angle with pure water of 20 ° or less, adheres only fountain solution, and repels ink. It has a non-image function that shows the characteristics.

An aniline electrolytic polymerization method is used to form a lipophilic surface to which ink adheres on the non-image surface of the silicate film with a small dot size. At this time, aniline is a polymer in an oxidized state and has a low solubility in water and forms a lipophilic film having a pure water contact angle of 70 ° or more. Potassium chloride is used as an electrolyte for imparting conductivity to the aniline aqueous solution.

Further, in order to form the lipophilic film into a minute dot size, it is necessary to generate a spot-like negative potential on the surface of the roller electrode 4 equivalent to the minute dot size. For this purpose, a narrow laser beam is irradiated from the inside of the roller electrode to the contact nip with the plate cylinder, and the opposite plate cylinder surface is exposed to negative electromotive force generated using the photoelectric conversion function. A polymer film of aniline having a small halftone dot size is formed on the positive electrode. Printing is performed using a plate material in which an image portion is formed as a halftone dot on the entire non-image portion formed as described above.

After the printing is completed, it is necessary to temporarily erase the pattern and reproduce the image in an initial non-image state. Therefore, the plate material side is used as a negative electrode, and the electropolymerized aniline is changed from an oxidized state to a reduced state. . Aniline in a reduced state has high solubility in water and is easily dissolved and removed in water. In this way, the aniline on the surface of the plate cylinder is completely removed, and the plate is reproduced in the initial non-image state, so that preparation for the next pattern writing can be completed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a configuration diagram when the plate material according to the embodiment of the present invention is incorporated in an offset printing machine, and FIG. 2 is a configuration diagram showing the writing and erasing procedures of the plate material.

In FIG. 1, 1 is a plate cylinder, 2 is a plate-shaped plate material wound around the outer periphery of the plate cylinder 1, 7 is a blanket cylinder, and 4 is a roller electrode. The surface of the plate 2 can be supplied with an ink 6, an aniline, a potassium chloride aqueous solution 3, a regeneration aqueous solution 8, and a dampening solution 5.

A plate material 2 having a non-drawing surface wound on the entire surface of the plate cylinder 1 is formed on a stainless steel plate (JIS-SUS304) having a thickness of 0.3 mm and has a thickness of 1 to 2 μm. Chromium plating with a surface roughness Ra of 0.7 μm, and then a silicate coating 21 (see FIG. 2) having a thickness of 0.5 μm deposited using an electrodeposition bath of sodium silicate No. 3. And the pure water contact angle is 20 °. While rotating the plate 2 through the plate cylinder 1, an aqueous solution 3 of aniline and potassium chloride having a concentration of 0.1 mol / liter is applied to the plate 2 using a roller.

Next, an image portion having a pure water contact angle of 73 ° is formed by using a roller electrode 4 made of a photoelectric conversion material for writing provided immediately after (in the rotational direction) the application portion of the aqueous solution 3. Let me know. Semiconductor laser for writing (not shown)
Is stored inside the roller electrode 4 and is applied to a nip between the plate cylinder 1 and the roller electrode 4.

The dampening water 5 and the ink 6 are supplied in a thin film state using a roller for application to the plate cylinder 1 on which the image is formed as described above to form an image. And transfer it to printing paper (not shown).

After the printing is completed, the image portion on the plate surface of the plate cylinder 1 is erased in the following procedure. That is, while supplying an aqueous solution for regeneration 8 containing an electrolyte such as potassium chloride to the plate cylinder 1 via the roller 9, a current is applied using the roller 9 as a positive electrode and the plate 2 as a negative electrode. Thereby, the polymerized aniline on the plate is dissolved in the aqueous solution 8 and removed from the plate.

The plate material 2 can be reused by re-creating a silicate electrodeposition film when the non-image function disappears.

FIG. 2 shows a modeled writing / erasing process of the plate material 2. In FIG. 2, reference numeral 20 denotes a stainless steel plate whose surface is subjected to the chrome plating,
The silicate film 21 is formed on the surface thereof, and then writing and erasing are performed by switching the positive electrode and the negative electrode of the electrode (using a needle electrode).

[0026]

The present invention is configured as described above.
According to the present invention, digital print manuscript information, such as characters and images, edited on a computer can be written directly on a plate cylinder using a semiconductor laser or the like without using a film. This saves expensive films and eliminates the need for a developing solution, thereby making it possible to reduce plate making costs, reduce plate making time, and facilitate plate making changes.

Since the resolution that governs image quality depends on the diameter of the semiconductor laser beam, the resolution can be improved by using a small-diameter beam relatively easily.

Furthermore, it is possible to obtain a reproducible printing plate material which can be written and erased only by using inexpensive and non-hazardous aniline, potassium chloride or the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram when a plate material according to an embodiment of the present invention is incorporated in an offset printing press.

FIG. 2 is a configuration diagram showing a procedure for writing and erasing the plate material.

[Explanation of symbols]

 Reference Signs List 1 plate cylinder 2 plate material 3 aniline / potassium chloride aqueous solution 4 roller electrode 6 ink 7 blanket cylinder 8 regeneration aqueous solution 20 steel plate (substrate) 21 silicate film

Claims (3)

[Claims] 1. A printing plate which is wound around a plate cylinder of a printing machine and is subjected to printing, wherein a silicate film is formed on a chromium plating layer, and aniline which can be erased on an image portion on the surface of the silicate film. A printing plate characterized by forming a polymer film. 2. A silicate film is formed on a chromium plating layer applied to the surface of a substrate, and aniline and an aqueous solution of potassium chloride are applied to the surface of the silicate film. A method for producing a printing plate, characterized in that electrolytic polymerization is carried out by applying a current to a negative electrode side, and then the remaining aqueous solution is removed to form an image area. 3. An electrolytic solution is applied to the surface of the printing plate after the image portion is formed, and the chromium plating layer is used as a negative electrode and the image portion is used as a positive electrode to dissolve and remove the image portion. The method for producing a printing plate according to claim 2.