Letterpress printing plate precursor

Abstract

To provide a letterpress printing plate precursor that enables the production of a letterpress printing plate with excellent visibility for displayed information.SOLUTION: A letterpress printing plate precursor has a relief-forming layer on a support. The letterpress printing plate precursor has at least two visual information engravings on the side of the support that is opposite the relief-forming layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a relief printing plate precursor. [Background technology]

[0002] Letterpress printing is widely used for various printing on paper, plastic films for packaging, containers, labels, metals, etc. In these printing processes, letterpress printing plates cut to a desired size are used according to the size of the printed matter.

[0003] On the other hand, for waterless lithographic printing plate precursors used in offset printing, surface treatment of the back surface of the support has been considered for purposes such as lot management of printing plates. For example, a waterless lithographic printing plate precursor having at least a photosensitive resin layer and a silicone layer on a support has been proposed, characterized in that the side of the support not having the photosensitive resin layer is engraved by irradiating it with laser light (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-31117 A Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of process control, etc., it is also required for letterpress printing plates to directly display various information. One possible method for displaying information is, for example, printing such as inkjet printing on the back surface of the substrate, but such a method has a problem in visibility, as the display is easily erased by rubbing or solvent during handling. Therefore, the present invention has an object to provide a letterpress printing plate precursor that can provide a letterpress printing plate with excellent visibility of displayed information. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention mainly has the following configuration. (1) A letterpress printing plate precursor having a relief-forming layer on a support, the letterpress printing plate precursor having two or more visual information marks on the surface of the support opposite to the relief-forming layer. (2) The letterpress printing plate precursor according to (1), having the markings at equal intervals in a fixed direction. (3) The letterpress printing plate precursor according to (1) or (2), wherein the visual information includes letters, symbols, codes, numbers, figures and / or patterns. (4) The letterpress printing plate precursor according to any one of (1) to (3), wherein the visual information includes information on a manufacturing date and time of the letterpress printing plate precursor. (5) The letterpress printing plate precursor according to any one of (1) to (4), wherein the visual information includes position information in the manufacturing direction and / or width direction of the letterpress printing plate precursor. (6) The letterpress printing plate precursor according to any one of (1) to (5), wherein the depth of the engraving is 0.1 μm or more and 4 μm or less. Effect of the Invention

[0007] According to the letterpress printing plate precursor of the present invention, it is possible to obtain a letterpress printing plate having excellent visibility of displayed information. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic diagram showing the position of an imprint on the letterpress printing plate precursor produced in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The letterpress printing plate precursor according to the present invention is a precursor of a letterpress printing plate used in letterpress printing, and has a relief-forming layer on a support. An adhesive layer or the like may be present between the support and the relief-forming layer, and a mask layer or a protective film may be present on the relief-forming layer. The letterpress printing plate precursor according to the present invention has two or more visual information imprints on the surface opposite the relief-forming layer of the support. By having visual information on the surface opposite the relief-forming layer (back surface), information can be displayed without affecting relief formation. Furthermore, by having visual information imprints, unlike displays using ink, they are not easily erased by rubbing or solvents during handling, and have excellent visibility. Furthermore, by having two or more visual information, traceability is excellent even when the letterpress printing plate precursor is cut to fit the size of the printing machine to be used.

[0010] The visual information referred to here refers to information that appeals to the visual sense, such as letters, symbols, codes, numbers, figures, patterns, etc. Two or more of these may be combined. Moreover, visually appealing means that it can be recognized visually, regardless of whether it has a design or not. The mark in the present invention is preferably one that can be recognized through light reflected by the support.

[0011] The support is preferably made of a material having excellent dimensional stability. Specific examples include a film such as PET, and a metal plate such as steel, stainless steel, and aluminum. Two or more of these may be used.

[0012] The thickness of the support is preferably 100 to 350 μm from the viewpoints of handling and flexibility.

[0013] The relief-forming layer is a layer that becomes a relief in a letterpress printing plate. Examples of the relief-forming layer include a photosensitive resin layer that undergoes polymerization by absorption of electromagnetic energy rays such as ultraviolet light and becomes insoluble in a developer, and a resin layer that can be engraved into a desired shape by electromagnetic energy rays such as laser light. The photosensitive resin layer can form a desired relief by, for example, irradiating it with ultraviolet light imagewise. Among these, the photosensitive resin layer is preferred from the viewpoint of productivity and image reproducibility of the letterpress printing plate. The photosensitive resin layer preferably contains a resin, a photopolymerization initiator, and a compound having an ethylenic double bond.

[0014] The thickness of the relief-forming layer is preferably 0.1 to 3 mm.

[0015] In the present invention, it is preferable that the markings are equally spaced in a certain direction. For example, the markings may be equally spaced in the manufacturing direction when the letterpress printing plate precursor is manufactured, and the manufacturing direction can be specified from the direction of multiple markings, which is more excellent in traceability. Similarly, the markings may be equally spaced in the direction perpendicular to the manufacturing direction when the letterpress printing plate precursor is manufactured, i.e., in the width direction, or may be equally spaced in both the manufacturing method and the width direction. In addition, as described above, when the letterpress printing plate precursor or the letterpress printing plate obtained therefrom is cut to a desired size for use, the interval between the markings is set smaller than the expected size of the letterpress printing plate precursor or letterpress printing plate, so that visual information can be visually recognized even in the cut state, which is more excellent in traceability.

[0016] Examples of the visual information include lot information, production date and time information, and production direction and position information of the letterpress printing plate precursor.

[0017] It is preferable that the visual information includes manufacturing date and time information, which makes it easy to check against the manufacturing conditions at the time of manufacturing and the presence or absence of sudden defects, and is excellent in traceability. In particular, it is possible to quickly check against information such as surveillance camera footage of the manufacturing process, and it is possible to easily confirm the state of a specific occurrence of a sudden defect in the manufacturing process, which can be used to improve quality. The manufacturing date and time information can be displayed, for example, as a character string such as numbers, or as letters, codes, patterns, figures, etc. that are previously determined to correspond to the date and time, or these may be combined.

[0018] It is preferable that the visual information includes position information in the manufacturing direction and / or width direction of the letterpress printing plate precursor, which allows for easy identification of more detailed positions during the manufacture of the letterpress printing plate precursor, and therefore provides superior traceability. The position information can be displayed, for example, by character strings such as numbers, or letters, codes, patterns, figures, etc. that are previously determined to correspond to positions, or these may be combined.

[0019] The depth of the engraving is preferably 0.1 μm or more, which can further improve visibility. The depth of the engraving is more preferably 0.5 μm or more. On the other hand, the depth of the engraving is preferably 4 μm or less, which can suppress folding of the support when handling the letterpress printing plate precursor or the letterpress printing plate obtained therefrom. The depth of the engraving is more preferably 2 μm or less.

[0020] The relief printing plate precursor of the present invention can be obtained, for example, by melting a portion corresponding to a desired shape on the back surface of a support of a known relief printing plate precursor to form an inscription. More specifically, it is preferable to form the inscription by irradiating a laser such as a YAG laser, a CO2 laser, or a semiconductor laser. In this case, the output of the laser is preferably 5 to 50 W.

[0021] A letterpress printing plate obtained from the above-mentioned letterpress printing plate precursor has a relief layer on a support, and has two or more pieces of visual information imprinted on the back surface of the support.

[0022] Next, a method for manufacturing a letterpress printing plate using the letterpress printing plate precursor according to the present invention will be described. The method for manufacturing a letterpress printing plate preferably includes a step of forming a relief by partially removing the relief-forming layer of the letterpress printing plate precursor described above (a relief-forming step). Examples of the relief-forming step include a method of engraving the relief-forming layer into a desired shape using electromagnetic energy rays such as laser light, and when the relief-forming layer is a photosensitive resin layer, a method including an exposure step of partially photocuring the photosensitive resin layer and a development step of removing the uncured portion of the photosensitive resin layer with a developer. Among these, a method including an exposure step and a development step using a photosensitive resin layer as the relief-forming layer is preferred from the viewpoints of productivity and image reproducibility of the printing plate. EXAMPLES

[0023] The present invention and its effects will be described below using specific examples, but the scope of application of the present invention is not limited to these examples.

[0024] [Example 1] On the back surface of the steel support of the photosensitive resin letterpress printing plate precursor "Treleaf" (registered trademark) WS73HII cut to 650 mm x 550 mm, three types of markings, marking 1 "5 / 17 10:00 A", marking 2 "5 / 17 10:00 B", and marking 3 "5 / 17 10:00 C", were formed at intervals of 150 mm in the width direction using a 3Axis hybrid laser marker MD-X2020A (manufactured by Keyence Corporation). Here, 5 / 17 10:00 indicates the date and time of manufacture, and the letters A to C indicate the position information in the width direction. Figure 1 shows a schematic diagram showing the positions of the markings. Each character of the marking was 12 pt in size, Arial font, and the depth of the marking was 1.1 μm. The resulting letterpress printing plate precursors were cut to 300 mm x 200 mm, and the visual information was visible on each plate. Furthermore, when the engraved area was rubbed 10 times with a cloth soaked in isopropyl alcohol and another cloth soaked in ethanol, and then visually inspected, the visual information was visible on each plate.

Claims

1. A letterpress printing plate precursor having a relief-forming layer on a support, the letterpress printing plate precursor having two or more visual information marks on the surface of the support opposite to the relief-forming layer.

2. 2. The letterpress printing plate precursor according to claim 1, wherein the markings are arranged at equal intervals in a fixed direction.

3. The letterpress printing plate precursor according to claim 1 or 2, wherein the visual information includes a letter, a symbol, a code, a number, a figure and / or a pattern.

4. The letterpress printing plate precursor according to claim 1 or 2, wherein the visual information includes information on a manufacturing date and time of the letterpress printing plate precursor.

5. The letterpress printing plate precursor according to claim 1 or 2, wherein the visual information includes position information in the manufacturing direction and / or width direction of the letterpress printing plate precursor.

6. 3. The letterpress printing plate precursor according to claim 1, wherein the depth of the inscription is from 0.1 [mu]m to 4 [mu]m.

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