JPH07101308B2 - Method for forming image area of waterless planographic printing plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming an image area of a waterless lithographic printing plate capable of printing without fountain solution.

[Prior Art] Waterless lithographic printing is that the image area and the non-image area are basically on the same plane, and the image area is ink-receptive and the non-image area is ink-repellent. In lithographic printing, in which ink is applied only to the image area by using the difference in ink adhesion, and then the ink is transferred to the printing material such as paper to print, the non-image area repels the ink. Consisting of a material layer having properties,
It means a printing plate that can be printed without using fountain solution.

As the waterless lithographic printing plate having excellent performance in practical use, one using a silicone rubber layer as a material layer having ink repulsion property, for example, JP-B-54-269.
23 and JP-A-56-80046 are known. Since these waterless planographic printing plates do not require dampening water during printing, they can be said to have many advantages in terms of workability during printing, print quality, and the like.

By the way, during the actual printing operation, after performing normal exposure and development processing and making a printing plate, it becomes clear that the image lines are missing.Therefore, newly write image lines such as characters and lines in the non-image areas. When adding, or when making a relatively large area of the appropriate part of the non-printing area on the plate surface to create a new printing area, it is necessary to make the non-printing area new. May occur. In particular, when the latter non-image area having a relatively large area needs to be made into an image area, there is a “ghost” countermeasure that occurs at the time of printing. Here, “ghost” refers to a phenomenon in which a decrease in ink density occurs in a part of a printed matter due to defective ink transfer, and for example, a pattern in which the ink adhesion amount is extremely different between the left and right sides of the printing plate. When a printing plate (for example, one with more right side than left side ... The obtained printed matter has more ink adhering amount on the right side than ink adhering amount on the left side), when the printing plate is The amount of ink supplied from the inking roller to the plate surface during rotation of the mounted plate cylinder cylinder varies greatly in the left-right direction of the plate (axial direction of the cylinder). Therefore, a shortage of ink supply from the inking roller to the printing plate surface occurs partially, especially on the side with a large amount of ink adhered, and a decrease in ink density occurs on a part of the printed matter (the latter half of the rotation of the plate cylinder cylinder). Means that. This "ghost"
Once this occurs, the printing method cannot avoid this phenomenon, so it is common to deal with it by the method described below.

That is, for example, when a "ghost" occurs in the lower left portion of the obtained printed matter, either one of the "ghost" portion and the pattern above the "ghost" portion is erased (erasing is an image area portion. Is made non-image area), and the ink consumption is balanced in the left-right direction, so that a printed matter with a normal ink density is printed once.
After that, a printing plate having only the erased portion is prepared, and additional printing is performed again to finally print the printed matter on which the normal portion is printed.

Furthermore, when erasing is generally performed on a waterless planographic printing plate, for example, as proposed in JP-B-61-3417,
Since a method of forming a new ink-repellent layer on the image area to be erased to make it non-image area is used, once erase is applied to the plate surface, the erased area is restored to the original state. Cannot be returned to. Because the above-mentioned erased part (the part where the ink repellent layer is newly formed and the non-image area is formed)
Is firmly adhered to the image area of the lower layer. Therefore, when this method is used, two types of printing plates are required to print one printed matter, and moreover, printing has to be performed twice, which is an inefficient solution. there were. In other words, once erased on the printing plate surface, the erased part cannot be restored to its original state, so that a printing plate of only such erased part is required.

On the other hand, as another countermeasure against "ghost", a method of additionally forming an image area to balance the ink consumption in the left and right directions is conceivable. That is, when a "ghost" occurs on the left side part, instead of erasing one of the parts as described above, the part that is discarded when the paper is cut,
By recreating the image consumption part (ink receiving part), which is the outer margin of the so-called "cut", to rebalance the ink consumption in the left-right direction,
It is a method to eliminate the "ghost". Several methods have been proposed in the past as specific methods for additionally forming the image area, which is the ink consuming portion.

For example, in Japanese Patent Laid-Open No. 55-60948, a heated metal rod is pressed against a portion of the silicone rubber layer, which is an ink repellent layer on the printing plate surface, to be newly imaged, and the portion is used as an ink receiving portion. A method of forming an image area has been proposed. This method is a very effective method as a method for forming a fine portion in a drawing area. However, this method is inferior in practicality in order to newly form a relatively large area image area on the printing plate surface.

That is, in order to press the printing plate surface with a medium heated to a high temperature over a wide range, a large jig is required, which is complicated. Further, since the temperature is high, there is a risk of burns and the like, and there is a problem that the practicality is poor.

Another simple method for forming additional image areas is to remove the silicone rubber layer on the plate surface mechanically with sandpaper or a cutter to expose the ink-receptive surface and create a new image area. There are possible ways to do this. However, this method is inferior in practicability because chips and the like are likely to be generated, and the generated chips adhere to the surface of the printing plate to stain it and damage the silicone rubber layer of the printing plate. In addition, since this method damages the printing plate surface during the additional formation of the image area, if it is necessary to return the portion where the image area is additionally formed to the non-image area after performing this method once, for example, more than necessary. In the case where the area of (1) is made into the image area, the additional formed area has to be erased again, which becomes complicated and inferior in practicality.

[Problems to be Solved by the Invention] The present inventors have solved such problems, have good workability, and are capable of simply and completely forming a relatively large area image area on a printing plate surface. The present invention has been achieved as a result of intensive studies to obtain a method for newly forming a portion.

[Means for Solving the Problem] That is, the present invention has the following configuration.

(1) In a waterless planographic printing plate having a silicone rubber layer as an ink repellent layer, an adhesive force of 50 g was applied to a portion of the non-image area of the silicone rubber layer corresponding to a portion to be removed when trimming a printed matter. A method for forming an image area of a waterless lithographic printing plate, characterized in that a sheet having an ink-receptive surface is attached via an adhesive layer of not less than 1 cm / cm, and the portion to which the sheet is attached is made an image area. .

(2) The method for forming an image area according to claim (1), wherein the adhesive layer is formed of a silicone adhesive.

The waterless lithographic printing plate having the silicone rubber layer as the ink repellent layer used in the present invention may have a plate constitution in which the silicone rubber layer which is the ink repellent layer is the uppermost layer, or the silicone rubber layer The plate structure may have a photosensitive layer on the top. Alternatively, the silicone rubber layer may be simply formed on the base material. That is, the present invention can be widely applied as a method of forming the image area on the surface of the silicone rubber layer which is the ink repellent layer.

Further, the waterless planographic printing plate mainly means a printing plate which has been subjected to an ordinary exposure and development treatment, but it may be an untreated printing plate, and the present invention can be applied to any surface of the silicone rubber layer even if it has undergone any history. The effect of is fully expressed.

In the present invention, the non-image area means the surface of the silicone rubber layer which is the ink repellent layer of the waterless planographic printing plate, and the surface of the silicone rubber layer has been subjected to an exposure and development treatment or an inking treatment. Or may be completely untreated.

In the present invention, the image area means an ink-receptive surface other than the above-mentioned non-image area.

Materials used for the sheet having an ink-receptive surface used in the present invention include paper and polyester film,
Sheets that have little or no ink repulsion, such as polypropylene films, cellophane, and various plastic films such as polyethylene films,
It can be used without any restrictions. In particular, polyester films and polypropylene films are preferably used because they are thin, tough, and inexpensive.

As the pressure-sensitive adhesive layer, various pressure-sensitive adhesives and polymers can be used, but since the printing plate surface is preferably a silicone rubber layer, in order to effectively develop the pressure-sensitive adhesive force with the substrate, a silicone-based adhesive is used. It is particularly preferable to use the pressure-sensitive adhesive. That is, in order to overcome the intense share applied to the plate surface during printing and firmly adhere to the plate surface, the adhesive force between the substrate and the plate surface is 50% in the following measurement method.
It is necessary to be g / cm or more, preferably 10 g / cm or more. When using this sheet with an adhesive strength of less than 50 g / cm, the frequency of “peeling” or “wrinkling” from the plate surface increases due to the strong share added to the plate surface during printing, making it practical. Inferior.

Next, a method of measuring the adhesive force will be described.

That is, in a 23 ° C. 63% RH environment, Tensilon (manufactured by Toyo Baldwin Co., Ltd.) was placed on a sample (the sheet was previously attached to the non-image area of the printing plate surface) at a peeling angle of 160 °. After mounting, the sheet is peeled from the plate surface at a peeling speed of 200 mm / min. The peel resistance value is measured with a load cell (max 1 kg) and recorded in a recorder. The recorded value (weight) is standardized by the width (length) of the sheet, and this is defined as the above-mentioned adhesive force. Generally g /
Units of cm are used.

Examples of the pressure-sensitive adhesive that exhibits these pressure-sensitive adhesive strengths include silicone pressure-sensitive pressure-sensitive adhesive SH-4280 (manufactured by Toray Silicone Co., Ltd.) or KR101-10 (Shin-Etsu Chemical Co., Ltd.).
Manufactured) etc. These pressure-sensitive adhesives may be used alone for forming the pressure-sensitive adhesive layer, or may be used as a mixture with a non-silicone pressure-sensitive adhesive, if necessary.

Even if this adhesive layer is previously applied to the sheet,
It may be applied immediately before sticking or any of them may be applied.

Examples of advantageous embodiments used in the present invention include pressure-sensitive adhesive tapes that are generally widely commercially available, and those having the above-mentioned sheet and pressure-sensitive adhesive layer include, for example, 558A, 558B, 558T, 578A, 578B ( Both are manufactured by Nichiban Co., Ltd.

Next, the application method of the present invention will be described. First, an ink-receptive sheet is attached onto the silicone rubber layer, which is a non-image area to be newly image-formed, via the above-mentioned adhesive layer. The adhesive layer may be formed on the silicone rubber layer or may be formed on the sheet. That is, the above-mentioned pressure-sensitive adhesive may be applied onto the silicone rubber layer, which is a non-image area to be newly image-formed, or onto the sheet. Preferably, the pressure-sensitive adhesive is applied on the sheet in advance and prepared as a pressure-sensitive adhesive tape, and when it becomes necessary to apply the present invention, the tape is cut into a necessary area and shape, and a new image is drawn. It is preferable to stick it on the silicone rubber layer, which is the non-image area to be partially formed.

INDUSTRIAL APPLICABILITY The present invention can be applied to a printing method in which a silicone rubber layer is used as an ink repellent layer, in which a portion of the silicone rubber layer corresponding to a portion to be removed when trimming a printed matter is newly imaged. That is, it can be preferably applied to a waterless planographic printing plate in which the non-image area is a silicone rubber layer, and the sheet is simply stuck on the silicone rubber layer of the sheet-shaped support having the silicone rubber layer as the uppermost layer. It can also be applied to a method of forming a lined portion and forming a patterned image portion.

[Examples] The present invention will be described in more detail with reference to the following examples.

Example 1 A Toray waterless lithographic plate (manufactured by Toray Industries, Inc.) of Kikuzen size (800 × 1030 mm) was exposed and developed to form a printing plate, and then offset printing four-color machine (“Lithrone 40” manufactured by Komori Printing Co., Ltd.) The plate was mounted on the plate, and ordinary four-color lithographic printing was performed. A ghost occurred because the balance of the ink supply in the left-right direction of the black color plate was broken in the design. As a countermeasure, it is necessary to form a new image area in a part of the non-image area in the margin of the pattern on the plate surface to balance the ink supply in the horizontal direction of the plate.

Therefore, an adhesive tape 578A (manufactured by Nichiban Co., Ltd .; base polyester film) having a silicone-based adhesive layer on the non-image area (silicone rubber layer surface) in the margin of the printing plate surface [adhesive strength: ~ 120 g / cm] was pasted in a size of 18 mm × 200 mm. As a result of printing again, the area where the above-mentioned adhesive tape was adhered was imaged because the back surface (non-adhesive layer side) of the tape was completely ink-receptive.
In addition, by forming a new image area, the balance of ink supply in the horizontal direction of the printing plate was restored and the ghost was eliminated. Even after 10,000 sheets were printed, the above-mentioned pressure-sensitive adhesive tape had no tendency to "wrinkle" or "peel off" and strongly adhered to the surface of the silicone rubber layer which was a non-image area.

Example 2 In the same manner as in Example 1, an adhesive tape was attached to form an image area, and after 10,000 sheets had been printed, the adhesive tape was peeled off and printed again. It was possible to obtain a printed matter similar to the one before it was pasted with the image area.

Comparative Example 1 As in Example 1, a part of the non-image area of the printing plate needed to be newly made into an image area. Rubbing with (# 1000), the silicone rubber layer was mechanically removed, and the photosensitive layer was exposed to form an image area. When printed again, not only the silicone rubber layer but also the aluminum substrate was partially scraped off, so aluminum scraps adhered to the printing plate surface, causing numerous scratches on other necessary non-image area silicone rubber layers. Occurred, and ink stains were generated on the printed matter.

Comparative Example 2 Polyester film “Lumirror” (manufactured by Toray Industries, Inc .; thickness of 50 μm) was used as a silicone pressure sensitive adhesive SH-4280.
(Toray Silicone Co., Ltd.) was applied at a thickness of about 15 g / m ² and dried to give an adhesive tape [adhesive strength; -40 g / cm].
This tape was cut into a size of 18 mm x 150 mm, and the tape was attached and printed in the same manner as in Example 1, and after printing about 2,000 sheets, "wrinkles" and "peeling" were observed on the tape. Had occurred.

Example 3 As in Example 1, a part of the non-image area of the printing plate needed to be newly made into an image area. A pressure sensitive adhesive SH-4280 (manufactured by Toray Silicone Co., Ltd.) was applied at a thickness of about 70 g / m ² . When the solvent contained in the pressure-sensitive adhesive was evaporated and dried, a polyester film "Lumirror" (manufactured by Toray Industries, Inc .; thickness of 50 microns) was attached in a size of 18 mm x 150 mm [adhesive strength; ~ 200 g / cm]. When printing was performed again after this, the above-mentioned film-attached portion was completely ink-receptive and had an image area. Even after printing 5,000 sheets, there was no tendency for "wrinkles" or "peeling" on the film.

[Advantageous Effects of the Invention] According to the present invention, when it becomes necessary to newly form a non-image area on the printing plate surface, an adhesive tape or the like can be attached to easily and securely form an image area having a relatively large area. Can be formed into Further, the tape can be peeled off if necessary, and the part which has once become the image area can be easily returned to the original non-image area.

INDUSTRIAL APPLICABILITY The present invention is very effective as a countermeasure against ghosts, because the image area forming method is applied to a portion of the silicone rubber layer corresponding to a portion to be removed when trimming a printed matter. Further, for example, even when the ink stays on the printing press roller, the ink can be easily consumed.

Claims (2)

[Claims] 1. A waterless lithographic printing plate comprising a silicone rubber layer as an ink repellent layer, wherein a non-image area of the silicone rubber layer is adhered to a portion corresponding to a portion to be removed when trimming a printed matter. An image part of a waterless lithographic printing plate characterized by sticking a sheet having an ink-receptive surface through an adhesive layer having a force of 50 g / cm or more, and making the part where the sheet is stuck into an image part Forming method. 2. The method for forming an image area of a waterless planographic printing plate according to claim 1, wherein the adhesive layer is formed of a silicone adhesive.