Method for producing a gravure photosensitive resin printing plate

Abstract

To provide a method for manufacturing a photosensitive resin printing plate for intaglio printing which eliminates problems of image collapse due to film adhesion failures caused by film use in exposure, and an unclear image due to light scattering in a film.SOLUTION: A photosensitive resin printing plate for intaglio printing is manufactured by the steps of: preparing a photosensitive resin original plate having a support, a photosensitive resin layer and a heat-sensitive mask layer in this order; irradiating the heat-sensitive mask layer by a laser beam according to a predetermined pattern, performing melting and removing, and thereby forming a drawing pattern including an image part and a dot part formed therein in the heat-sensitive mask layer; irradiating the photosensitive resin original plate after the mask layer drawing step with ultraviolet light from the side of the heat-sensitive mask layer; curing the photosensitive resin layer according to a drawing pattern of the heat-sensitive mask layer; and removing a non-exposed non-cured part of the photosensitive resin layer, after the image exposure step.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a photosensitive resin printing plate used for intaglio printing such as pad printing, and particularly to a method for manufacturing a photosensitive resin printing plate for intaglio that solves the problems of image blurring due to poor film adhesion caused by film use and image unclarity due to light scattering within the film.

Background Art

[0002] Intaglio printing is a printing method in which ink is stored in the recesses of the plate and transferred to a substrate, contrary to relief printing. It is used for printing substrates that are difficult to print with relief printing or offset printing, such as golf balls, computer keyboards, fabrics, and flexible packaging materials other than paper. It is also widely used in applications that require printing densities that cannot be obtained by other printing methods or fine printing.

[0003] As such intaglio printing, there is known pad printing in which the ink stored in the recesses of the plate is first transferred to an elastic silicone pad or the like, and then the ink is secondarily transferred from the silicone pad to the object to be printed (see Patent Document 1). Usually, in pad printing, after storing ink in the recesses of the plate, excess ink is removed with a squeegee or the like. At this time, in order to appropriately quantify the ink stored in the recesses, it is common to form a halftone dot portion in the recesses (image portions). Therefore, in pad printing, as shown in FIG. 1, in addition to (i) positive film adhesion and (ii) formation of recesses (image portions) by image exposure, in order to form a halftone dot portion in the recesses (image portions), (iii) screen film adhesion and (iv) screen exposure are further performed, and then (v) development is performed to generally manufacture an intaglio printing plate.

[0004] Specifically, (i) the emulsion surface of a positive film is overlapped with the photosensitive resin layer surface of the original plate and vacuum-bonded, and (ii) ultraviolet rays are irradiated in the state where the positive film is bonded to perform image exposure. After the image exposure is completed, the positive film is removed from the original plate. Next, (iii) the emulsion surface of a screen film for forming halftone dots is overlapped with the photosensitive resin layer surface of the original plate and vacuum-bonded, and (iv) ultraviolet rays are irradiated in the state where the screen film is bonded to perform screen exposure to form halftone dots. (v) Finally, the original plate is developed to remove the unexposed and uncured portions in the photosensitive resin layer, thereby manufacturing an intaglio printing plate.

[0005] However, in the conventional method such as in Patent Document 1, since it is necessary to closely arrange the positive film on the photosensitive resin layer for image exposure and closely arrange the screen film on the photosensitive resin layer for screen exposure, poor adhesion occurs during the close arrangement of these films, and dust and air bubbles easily enter between the film and the photosensitive resin layer, resulting in defective plates such as image blurring where fine characters and numbers are blurred.

[0006] In response to such problems, a method has been proposed for manufacturing an intaglio printing plate by a single exposure using an original film in which the original image portion (image portion) and halftone dots are integrated without performing exposure twice (see Patent Document 2). However, as long as a film is used in the method of Patent Document 2, the problem of poor film adhesion cannot be completely avoided, and there is still a problem that defective products occur. In addition, since image exposure is performed through the film, the irradiation light scatters and spreads within the film, the end portion of the image formation portion protrudes, the recess becomes small, and the printed image becomes unclear.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention was devised to solve the above problems of the prior art, and its object is to eliminate the problems of image collapse due to poor film adhesion caused by the use of film in image exposure and halftone dot exposure, and image blurring due to light scattering in the film, and to provide a method for manufacturing a photoresist printing plate for intaglio printing that eliminates these problems.

Means for Solving the Problems

[0009] As a result of intensive studies on a method for manufacturing a photoresist printing plate for intaglio printing without using a film, the present inventor has found that a heat-sensitive mask layer is previously formed on a photoresist layer instead of a film, and a drawing pattern including an image portion and halftone dot portions formed therein is formed on this heat-sensitive mask layer by laser ablation, whereby an intaglio printing plate having no problems of image collapse due to poor film adhesion caused by the use of film and image blurring due to light scattering in the film can be manufactured by a simple method, leading to the completion of the present invention.

[0010] That is, the present invention has the configurations of (1) to (3). (1) A preparation step of preparing a photoresist original plate having a support, a photoresist layer, and a heat-sensitive mask layer in this order, A mask layer drawing step of forming a drawing pattern including an image portion and halftone dot portions formed therein on the heat-sensitive mask layer by irradiating and melting the heat-sensitive mask layer with a laser according to a predetermined pattern, An image exposure step of irradiating the photoresist original plate after the mask layer drawing step with ultraviolet light from the heat-sensitive mask layer side and curing the photoresist layer according to the drawing pattern of the heat-sensitive mask layer, and A development step of removing the unexposed and uncured portions of the photoresist layer after the image exposure step A method for manufacturing a photoresist printing plate for intaglio printing, characterized by including the above steps. (2) The method for manufacturing a photopolymer printing plate for intaglio printing according to (1), wherein the heat-sensitive mask layer obtained in the mask layer drawing step has halftone dots with a line count of 200 to 400 lines per inch and an area ratio of 3 to 30% within the image area. (3) The method for manufacturing a photopolymer printing plate for intaglio printing according to (2), wherein the depth of the halftone dots of the printing plate is 30 to 60 μm.

Advantages of the Invention

[0011] According to the method of the present invention, instead of using a film as in the conventional method, an original plate having a heat-sensitive mask layer on a photosensitive resin layer is used, and a drawing pattern including an image area and a halftone dot area formed therein is formed on the heat-sensitive mask layer by laser ablation, and then image exposure, development, etc. are performed from the mask layer side. Therefore, problems such as image collapse due to poor film adhesion caused by the use of the film and image blurring due to light scattering in the film do not occur, and a photopolymer printing plate for intaglio printing with high printing quality can be manufactured by a simple method.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] Hereinafter, the method for manufacturing a photopolymer printing plate for intaglio printing of the present invention will be described in detail.

[0014] The method for manufacturing a gravure photosensitive resin printing plate of the present invention, without using a positive film or a screen film as in the prior art, as shown in FIG. 2, comprises the steps of: (i) preparing a gravure photosensitive resin original plate in which a support, a photosensitive resin layer, and a thermal mask layer are laminated in this order; (ii) forming a drawing pattern including an image portion and dot portions formed therein on the thermal mask layer by irradiating the thermal mask layer with a laser according to a predetermined pattern and melting and removing it; and (iii) sequentially performing an image exposure step of irradiating ultraviolet rays from above the drawn mask layer.

[0015] The gravure photosensitive resin original plate used in the manufacturing method of the present invention has a structure in which at least a support, a photosensitive resin layer, and a thermal mask layer are sequentially laminated.

[0016] The support used for the original plate is preferably a material that is flexible but has excellent dimensional stability. Examples include metal supports such as steel, aluminum, copper, and nickel, and thermoplastic resin supports such as polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, or polycarbonate film. Among these, a polyethylene terephthalate film having excellent dimensional stability and sufficiently high viscoelasticity is particularly preferred. The thickness of the support is desirably 50 to 350 μm, preferably 100 to 250 μm, considering mechanical properties, shape stability, or handleability during printing plate making. Further, if necessary, an adhesive may be provided between the support and the photosensitive resin layer to improve their adhesion.

[0017] The photosensitive resin layer used for the original plate is composed of essential components of a synthetic polymer compound, a photopolymerizable unsaturated compound, and a photoinitiator, and optional additives such as a plasticizer, a thermal polymerization inhibitor, a dye, a pigment, an ultraviolet absorber, a fragrance, or an antioxidant. The thickness of the photosensitive resin layer is preferably 100 to 600 μm, more preferably 200 to 500 μm, from the viewpoint of the dot depth.

[0018] As the synthetic polymer compound, conventionally known soluble synthetic polymer compounds can be used. For example, polyether amides (e.g., Japanese Patent Application Laid-Open No. 55-79437), polyether ester amides (e.g., Japanese Patent Application Laid-Open No. 58-113537), tertiary nitrogen-containing polyamides (e.g., Japanese Patent Application Laid-Open No. 50-76055), ammonium salt type tertiary nitrogen atom-containing polyamides (e.g., Japanese Patent Application Laid-Open No. 53-36555), addition polymers of amide compounds having one or more amide bonds and organic diisocyanate compounds (e.g., Japanese Patent Application Laid-Open No. 58-140737), addition polymers of diamines having no amide bond and organic diisocyanate compounds (e.g., Japanese Patent Application Laid-Open No. 4-97154), etc. Among them, tertiary nitrogen atom-containing polyamides and ammonium salt type tertiary nitrogen atom-containing polyamides are preferred.

[0019] As the photopolymerizable unsaturated compound, ring-opening addition reaction products of polyglycidyl ethers of polyhydric alcohols with methacrylic acid and acrylic acid can be mentioned. Examples of the polyhydric alcohol include dipentaerythritol, pentaerythritol, trimethylolpropane, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, ethylene oxide adduct of phthalic acid, etc. Among them, trimethylolpropane is preferred.

[0020] Examples of the photopolymerization initiator include benzophenones, benzoins, acetophenones, benzyls, benzoin alkyl ethers, benzyl alkyl ketals, anthraquinones, thioxanthones, etc. Specifically, benzophenone, chlorobenzophenone, benzoin, acetophenone, benzyl, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyldimethyl ketal, benzyldiethyl ketal, benzyldiisopropyl ketal, anthraquinone, 2-ethylanthraquinone, 2-methylanthraquinone, 2-allyl anthraquinone, 2-chloroanthraquinone, thioxanthone, 2-chlorothioxanthone, etc.

[0021] The heat-sensitive mask layer used in the original plate is composed of carbon black, which is a material having a function of absorbing infrared laser and converting it into heat and a function of blocking ultraviolet light, and its dispersion binder. As the dispersion binder, those conventionally known can be used. Further, as optional components other than these, a pigment dispersant, a filler, a surfactant, a coating aid, etc. can be contained within a range not impairing the effects of the present invention.

[0022] The weight ratio of carbon black to the dispersion binder in the heat-sensitive mask layer is preferably 25 to 50:20 to 75. If the weight ratio of the two is not within the above range, there is a possibility that the light-shielding property by carbon black cannot be achieved with a thin layer.

[0023] The heat-sensitive mask layer preferably has an optical density of 2.0 or more with respect to actinic rays, more preferably an optical density of 2.0 to 3.0, and particularly preferably an optical density of 2.2 to 2.5.

[0024] The layer thickness of the heat-sensitive mask layer is preferably 0.5 to 2.5 μm, more preferably 1.0 to 2.0 μm. If the layer thickness is less than the above lower limit, high coating technology is required and there is a possibility that the necessary optical density cannot be obtained. Further, if it exceeds the above upper limit, high energy is required for the evaporation of the heat-sensitive mask layer, which is disadvantageous in terms of cost.

[0025] Before using the original plate, it is preferable to provide a peelable flexible cover film on the heat-sensitive mask layer to protect the printing original plate. Examples of suitable peelable flexible cover films include polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene terephthalate film. However, such a protective film is not absolutely necessary.

[0026] It is also possible to provide an oxygen barrier layer between the heat-sensitive mask layer and the photosensitive resin layer. By providing the oxygen barrier layer, the curing inhibition by oxygen during the main exposure can be suppressed, and the reproducibility of the dots in the image portion is improved. Examples of the components of the oxygen barrier layer include polyvinyl alcohol and polyamide.

[0027] The photosensitive resin original plate used in the manufacturing method of the present invention can be manufactured by a conventionally known method, but for example, it can be manufactured as follows.

[0028] First, components such as binders other than carbon black in the thermosensitive mask layer are dissolved in an appropriate solvent, and carbon black is dispersed therein to prepare a dispersion. Next, such a dispersion is applied onto a support for the thermosensitive mask layer (for example, a PET film), and the solvent is evaporated to create one laminate. Separately, a photosensitive resin layer is formed on a support by coating to create the other laminate. The two laminates thus obtained are laminated under pressure and / or heating such that the photosensitive resin layer is adjacent to the thermosensitive mask layer. Note that the support for the thermosensitive mask layer functions as the above-described peelable flexible cover film after the completion of the printing original plate.

[0029] Next, by irradiating and melting the thermosensitive mask layer of the photosensitive resin original plate prepared as described above with a laser according to a predetermined pattern, a drawing pattern including an image portion and dot portions formed therein is formed in a positive mode on the thermosensitive mask layer. Examples of suitable lasers include IR lasers such as an ND / YAG laser (1064 nm) or a diode laser (e.g., 830 nm). As an example of a suitable laser system, a commercially available laser system for computer plate-making technology can be used. For example, CDI Spark (Esco Graphics) can be used. This laser system includes a rotating cylindrical drum that holds the photosensitive resin original plate, a laser irradiation device, and a layout computer, and image information regarding the drawing pattern is directly transferred from the layout computer to the laser device.

[0030] An example of the mask layer after the mask layer drawing process is shown in FIG. 3. In FIG. 3, an image portion representing the character information "A" is shown in black, and dot portions therein are shown as white circles.

[0031] In the present invention, the drawing pattern is such that the thermal mask layer obtained in the mask layer drawing process forms a dot portion in the image portion so that the thermal mask layer has dots with a dot (screen) line number of 200 to 400 lines per inch and an area ratio of 3 to 30%, preferably 5 to 20% in the image portion. When the dot (screen) line number of the dots is less than the above range, the fine line shape is affected by the dots and becomes a jagged line, resulting in a decrease in fine line reproducibility. On the other hand, when it exceeds the above range, the dot reproducibility decreases and the area ratio decreases. Also, when the area ratio of the dots is less than the above range, the ink amount in the recesses becomes too large, resulting in a decrease in character reproducibility. On the other hand, when it exceeds the above range, the ink amount accumulating in the recesses becomes too small, so the image sharpness decreases. Note that the dot (screen) line number is defined by how many dots are in one inch (the fineness of the dots). Also, the area ratio of the dots is defined as the ratio of the total area of the white dots to the area of the image portion.

[0032] After the above-described mask layer drawing process, an image exposure process is performed in which ultraviolet rays are irradiated onto the photosensitive resin original plate from the mask layer side over the entire surface, and the photosensitive resin is cured according to the drawing pattern of the thermal mask layer. This process can also be performed with the plate attached to the rotating cylindrical drum of the laser system. However, if the plate is removed from the laser device and irradiated with a conventional flat irradiation unit, it can accommodate off-specification plate sizes. As the ultraviolet rays, those having a wavelength of particularly 300 to 400 nm can be used. As the light source, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a zirconium lamp, a carbon arc lamp, a fluorescent lamp for ultraviolet rays, etc. can be used.

[0033] After the image exposure process, development is carried out by a conventional method to remove the unexposed and uncured portions of the photosensitive resin layer from the photosensitive resin original plate, whereby a photosensitive resin printing plate for intaglio printing is obtained.

[0034] In the present invention, it is preferable that the depth of the halftone dots of the printing plate is 30 to 60 μm, preferably 35 to 50 μm. If the dot depth is less than the above range, the ink is insufficient, resulting in poor character density uniformity. On the other hand, if it exceeds the above range, there is a risk that the amount of ink is too much, resulting in poor character reproducibility.

[0035] The intaglio printing plate obtained by the manufacturing method of the present invention can be used for manufacturing printed matter by intaglio printing such as pad printing, in the same manner as the intaglio printing plate obtained by the conventional manufacturing method using a film.

[0036] The substrate to be printed on the intaglio printing plate obtained by the manufacturing method of the present invention is not particularly limited, but substrates that are difficult to print by letterpress or offset printing, such as golf balls, computer keyboards, fabrics, and flexible packaging materials other than paper, are particularly suitable.

[0037] Unlike the intaglio printing plate obtained by the conventional manufacturing method using a film, the intaglio printing plate obtained by the manufacturing method of the present invention does not have problems such as image blurring due to poor film adhesion caused by the use of the film or image unsharpness due to light scattering within the film. Therefore, it is particularly suitable for use in applications where printing densities that cannot be obtained by other printing methods are required or where fine printing is required, and can sufficiently meet the recent requirements for improving printing accuracy.

Examples

[0038] Hereinafter, the effects of the present invention will be shown more specifically with reference to examples, but the present invention is not limited thereto. In the examples, parts and percentages are shown on a weight basis unless otherwise specified. Also, the evaluation methods for the characteristics used in the examples and comparative examples are as follows.

[0039] <Dot (Screen) Line Number> The dot (screen) line number was set to a desired value in the image information of the computer.

[0040] <Dot Area Ratio> The dot area ratio was set to a desired value using the image information of a computer. The dot area ratio of the plate after laser drawing was determined by measuring the transmittance using a black-and-white transmission densitometer DM-520 (manufactured by Dainippon Screen Mfg. Co., Ltd.), and it was confirmed that there was no difference from the set value. In the case of Comparative Examples 1 and 2 of the conventional method using a film, the dot area ratio of the original film was determined by measuring the transmittance using a black-and-white transmission densitometer DM-520 (manufactured by Dainippon Screen Mfg. Co., Ltd.).

[0041] <Dot depth> The depth in the depth direction (support direction) of the cross-section of the slit portion was read using a projector (Nikon PROFILE PROJECTOR V-12B), and this was defined as the dot depth.

[0042] <100-μm fine line shape> An intaglio printing plate with a 100-μm-wide fine line was created, mounted on a pad printing machine (manufactured by TAMPOPRINT), and printed using Type R Black ink (manufactured by TAMPOPRINT). As the object to be printed, commercially available art paper without unevenness was used for the evaluation of image reproducibility. In addition, the same pad printing machine, ink, and object to be printed were used in the following evaluation methods for <character density uniformity>, <character reproducibility>, <image sharpness>, and <adhesion unevenness>. The 100-μm-wide fine line printed matter obtained was magnified with a 20-fold magnifying glass and the shape of the fine line was confirmed with the naked eye to evaluate the 100-μm fine line shape. The judgment criteria are as follows. 〇: No zigzag shape was confirmed at all. △: A zigzag shape was partially confirmed. ×: A zigzag shape was confirmed throughout the fine line.

[0043] <Character density uniformity> A 36-point (12.6 mm) character image was created with an intaglio printing plate and printed with a pad printing machine to obtain a printed matter. The character density uniformity was evaluated by visually checking for the presence of uneven ink density within the character. The judgment criteria are as follows. 〇: No uneven ink density was confirmed within the character image. △: Some parts with insufficient ink density were confirmed in the text image. ×: It was confirmed that ink density unevenness occurred throughout the text image.

[0044] <Character reproducibility> Gravure images were formed using thin lines with a width of 30 - 150 μm and an interval of 10 μm, and the character reproducibility of the printed matter was evaluated in the same way as the evaluation of character density uniformity. The judgment criteria are as follows. 〇: The minimum line width recognizable as a thin line was 50 μm or less. △: The minimum line width recognizable as a thin line was more than 50 μm and 80 μm or less. ×: The minimum line width recognizable as a thin line was more than 80 μm.

[0045] <Image sharpness> 100 - μm independent points were created by gravure, and the image sharpness of the printed matter was evaluated by checking the shoulder shape of the cross section. The judgment criteria are as follows. 〇: The edge shape of the concave top had no roundness at all, and the edge could be discriminated. △: The edge shape of the concave top had slight roundness, but the edge could be discriminated. ×: The edge shape of the concave top became round, and the edge could not be discriminated at all.

[0046] <Adhesion unevenness> A gravure printing plate was made using a test chart with thin lines having a width of 100 - 500 μm, independent points having a diameter of 100 - 500 μm, and a text image "A" of 3 - 36 points. The width of the 100 - μm thin lines of the obtained gravure printing plate was measured at 10 locations using a projector (Nikon PROFILE PROJECTOR V - 12B), and based on the reproducibility of the line width, it was confirmed whether blooming, which is an index of adhesion unevenness, occurred. The judgment criteria are as follows. 〇: All 100 - μm - wide thin lines were reproduced with a width of 95 - 100 μm. △: There was one or more measurement locations where the 100 - μm - wide thin lines were narrowed by more than 5 μm and 30 μm or less. ×: There was at least one measurement location where the 100-μm-wide thin line became narrower than 30 μm.

[0047] <Example 1> Preparation of a dispersion binder for a heat-sensitive mask layer As a dispersion binder, butyral resin and a polyamide containing a tertiary amine group were prepared. As the butyral resin, BM-5 manufactured by Sekisui Chemical Co., Ltd. was used. As the polyamide containing a tertiary amine group, the one synthesized as follows was used.

[0048] Synthesis of a polyamide containing a tertiary amino group 50 parts by weight of ε-caprolactam, 40 parts by weight of N,N'-di(γ-aminopropyl)piperazine adipate, 10 parts by weight of 3-bisaminomethylcyclohexane adipate, and 100 parts by weight of water were charged into an autoclave. After nitrogen substitution, it was sealed and gradually heated. When the internal pressure reached 10 kg / m 3 Water was distilled off until the pressure could no longer be maintained from that point, and it was returned to normal pressure in about 2 hours. Then, it was reacted at normal pressure for 1 hour. The maximum polymerization reaction temperature was 255 °C. As a result, a polyamide containing a tertiary amine group with a melting point of 137 °C and a specific viscosity of 1.96 was obtained.

[0049] Preparation of a dispersion for a heat-sensitive mask layer 27 parts of butyral resin and 39 parts of the polyamide containing a tertiary amine group as a dispersion binder were dissolved in a solvent, and 34 parts of carbon black was dispersed therein to prepare a dispersion for the thermosensitive mask layer. As the solvent, a mixed solution of methanol and ethanol at a weight ratio of 70:30 was used.

[0050] Preparation of a photosensitive resin composition for a photosensitive resin layer 52.5 parts of ε-caprolactam, 40.0 parts of N,N'-bis(γ-aminopropyl)piperazine adipate, 7.5 parts of 1,3-bisaminomethylcyclohexane adipate, and 100 parts of water were added to a reactor. After sufficient nitrogen substitution, it was sealed and gradually heated. When the internal pressure reached 10 kg / cm 2When the pressure reached [pressure value], the water in the reactor was gradually distilled off to return to normal pressure in about 1 hour, and then the reaction was carried out at normal pressure for 0.5 hour. The maximum polymerization temperature was 210 °C, and a transparent pale yellow polyamide-1 with a melting point of 140 °C and a specific viscosity of 1.83 was obtained.

[0051] 55.0 parts of polyamide-1, 7.7 parts of N-methyltoluenesulfonamide, 0.02 part of 1,4-naphthoquinone, 50.0 parts of methanol and 10 parts of water were mixed in a heating dissolution kettle equipped with a stirrer at 60 °C for 2 hours to completely dissolve the polymer. Then, 30.1 parts of an acrylic acid adduct of trimethylolpropane triglycidyl ether, 3.1 parts of methacrylic acid, 0.1 part of hydroquinone monomethyl ether, 0.3 part of ammonium sulfite and 1.0 part of benzyl dimethyl ketal were mixed and dissolved for 30 minutes. Next, the temperature was gradually raised to distill off methanol and water, and the mixture was concentrated until the temperature in the kettle reached 110 °C. At this stage, a fluid viscous photosensitive resin composition was obtained.

[0052] Preparation of a photosensitive resin original plate As a support for the heat-sensitive mask layer, a PET film (Toyobo Co., Ltd., E5000, thickness 100 μm) treated with a release agent on both sides was used. A dispersion for the heat-sensitive mask layer was coated on this film using a bar coater appropriately selected so that the layer thickness became 1.5 μm, and dried at 120 °C for 5 minutes to form a heat-sensitive mask layer. Separately, an adhesive was coated on a PET film (support) (Toyobo Co., Ltd., E5000, thickness 250 μm) to a thickness of 20 μm. The photosensitive resin composition was sandwiched between the adhesive-coated surface side and the heat-sensitive mask layer, and heated and pressed at 110 °C to obtain a gravure photosensitive resin printing original plate with a total thickness of 830 μm. Note that the support for the heat-sensitive mask layer functions as a peelable flexible cover film after the completion of the printing original plate.

[0053] The support (cover film) for the thermosensitive mask layer of the obtained intaglio photosensitive resin printing original plate was removed. This plate was wound around the rotating cylindrical drum of a laser system (CDI4530 manufactured by ESKO GRAPHICS), and a mask layer drawing process was performed in which the thermosensitive mask layer was irradiated with a laser according to a predetermined pattern and melted and removed to form a drawing pattern including an image portion and dot portions formed therein on the thermosensitive mask layer. The layout computer of the laser system was set so that the line number and area ratio of the dots would be the values shown in Table 1. After the mask layer drawing process, the plate was taken out and returned to a flat plane, and main exposure of irradiating ultraviolet rays from the thermosensitive mask layer side with a Philips TL-K 40W / 10R lamp (peak wavelength 370 nm, illuminance at 350 nm is 10 mW / cm 2 ) was performed for 60 seconds, and an image exposure process was performed to cure the photosensitive resin layer according to the drawing pattern of the thermosensitive mask layer. Next, a development process was performed to remove the unexposed and uncured portions of the photosensitive resin layer with tap water at 25°C using a brush-type washer (120 μmφ nylon brush, JW-A2-PD type manufactured by Nippon Denshi Seiki Co., Ltd.) to obtain a relief image. Further, after hot air drying at 70°C for 10 minutes, post-exposure was performed for 30 seconds to obtain a printing plate.

[0054] The intaglio photosensitive resin printing plate thus obtained was evaluated for printed matter. The evaluation results are shown in Table 1.

[0055] <Examples 2 to 8> The setting of the layout computer of the laser system was changed so that the line number and area ratio of the dots would be the values shown in Table 1, and the ultraviolet irradiation time in the image exposure process was changed as shown in Table 1 so that the depth of the dots would be the value shown in Table 1. Except for this, in the same manner as in Example 1, an intaglio photosensitive resin printing plate was manufactured, and the obtained printing plate was evaluated for printed matter. The evaluation results are shown in Table 1.

[0056] <Comparative Example 1> Comparative Example 1 corresponds to an example of a method for manufacturing an intaglio printing plate by a single exposure using an original film in which the original drawing portion (image portion) and dots in Patent Document 2 are integrated. First, an original film with a halftone area formed within the image area was created. Specifically, a black carbon film TK100 (manufactured by Takano Machinery Co., Ltd.) was mounted on a digital imager "CDI SPARK" (manufactured by Esco Graphics Co., Ltd.), and the laser output and drum rotation speed were set to conditions that reproduce a halftone screen with 300 lines per inch and an area of 20% in the image area, and an original film of a test chart used for evaluating adhesion unevenness was created. On the other hand, a photopolymerizable resin printing plate original for intaglio printing was prepared in the same manner as in Example 1 except that a slip layer was provided instead of the heat-sensitive mask layer. This photopolymerizable resin printing plate original for intaglio printing was vacuum-bonded with the original film, and main exposure was performed for 60 seconds by irradiating ultraviolet rays from the slip layer side with a Philips TL-K 40W / 10R lamp (peak wavelength 370 nm, illuminance at 350 nm is 10 mW / cm 2 ) to perform an image exposure process of curing the photopolymerizable resin layer according to the drawing pattern of the original film. Next, the original film was peeled off, and a development process was performed to remove the unexposed and uncured portions of the photopolymerizable resin layer with tap water at 25°C using a brush-type washer (120 μmφ nylon brush, JW-A2-PD type manufactured by Nippon Denshi Seiki Co., Ltd.) to obtain a relief image. After further drying with warm air at 70°C for 10 minutes, post-exposure was performed for 30 seconds to obtain a printing plate.

[0057] Regarding the photopolymerizable resin printing plate for intaglio printing obtained in this way, evaluation of the printed matter and evaluation of adhesion unevenness were performed. The evaluation results are shown in Table 1.

[0058] <Comparative Example 2> Comparative Example 2 is an example corresponding to a method of manufacturing an intaglio printing plate by two exposures using two separate original films without integrating the original image portion (image area) and the halftone, as in Patent Document 1. First, using the black carbon film TK100 (manufactured by Takano Machinery Co., Ltd.), original drawing films 1 having an image portion and original drawing film 2 having halftone dots with a line count of 300 lines and an area of 20% over the entire surface were produced by the CDI SPARK of a digital imager (manufactured by Esco Graphics Co., Ltd.). On the other hand, a photogravure photosensitive resin printing original plate was prepared in the same manner as in Example 1 except that a slip layer was provided instead of the heat-sensitive mask layer. The original drawing film 1 was vacuum-bonded to this photogravure photosensitive resin printing original plate, and main exposure (first exposure) of irradiating ultraviolet rays from the slip layer side was carried out for 60 seconds using a Philips TL-K 40W / 10R lamp (peak wavelength 370 nm, illuminance at 350 nm being 10 mW / cm 2 ). After peeling off the original drawing film 1, the original drawing film 2 was vacuum-bonded and main exposure (second exposure) of irradiating ultraviolet rays from the slip layer side was carried out for 60 seconds using a Philips TL-K 40W / 10R lamp (peak wavelength 370 nm, illuminance at 350 nm being 10 mW / cm 2 ), and an image exposure process of curing the photosensitive resin layer according to the drawing patterns of the original drawing film 1 and the original drawing film 2 was carried out. Next, the original drawing film 2 was peeled off, and a developing process of removing the unexposed and uncured portions of the photosensitive resin layer with tap water at 25°C using a brush-type washer (120 μmφ nylon brush, JW-A2-PD type manufactured by Nippon Denshi Seiki Co., Ltd.) was carried out to obtain a relief image. Further, after hot air drying at 70°C for 10 minutes, post-exposure was carried out for 30 seconds to obtain a printing plate.

[0059] Regarding the photogravure photosensitive resin printing plate thus obtained, evaluation of the printed matter and evaluation of adhesion unevenness were carried out. The evaluation results are shown in Table 1.

[0060]

Table 1

[0061] As can be seen from Table 1, in Examples 1 to 8 manufactured according to the manufacturing method that satisfies the requirements of the present invention, since no film is used, problems such as image blurring due to poor film adhesion caused by the use of the film and image unsharpness due to light scattering within the film do not occur. On the other hand, in Comparative Example 1 and Comparative Example 2 manufactured according to the conventional manufacturing method using a film, poor adhesion of the film ("adhesion unevenness") has occurred. Therefore, as can be seen from the fact that the evaluation of "character reproducibility" is "×", image blurring has occurred. Also, as can be seen from the fact that the evaluation of "image sharpness" is "×", problems of image unsharpness due to light scattering within the film have occurred.

Industrial Applicability

[0062] According to the method of the present invention, instead of using a film as in the prior art, an original plate having a thermal mask layer on a photosensitive resin layer is used, and a drawing pattern including an image portion and a halftone dot portion formed therein is formed on the thermal mask layer by laser ablation, and then image exposure, development, etc. are performed from the mask layer side. Therefore, problems such as image blurring due to poor film adhesion caused by the use of the film and image unsharpness due to light scattering within the film do not occur, and a gravure photosensitive resin printing plate with high printing quality can be manufactured by a simple method. Therefore, the present invention is particularly suitable for use in applications that require printing densities that cannot be obtained by other printing methods or fine printing, and can sufficiently meet the recent requirements for improving printing accuracy.

Claims

1. A preparation step of preparing a photosensitive resin original plate having a support, a photosensitive resin layer, and a thermal mask layer in this order, A mask layer drawing step of forming a drawing pattern including an image portion and a halftone dot portion formed therein on the thermal mask layer by irradiating and melting the thermal mask layer with a laser according to a predetermined pattern, An image exposure step of irradiating the photosensitive resin original plate after the mask layer drawing step with ultraviolet rays from the thermal mask layer side and curing the photosensitive resin layer according to the drawing pattern of the thermal mask layer, and A development step of removing the unexposed and uncured portions of the photosensitive resin layer after the image exposure step A method for manufacturing an intaglio photosensitive resin printing plate for pad printing, comprising: The thermal mask layer obtained in the mask layer drawing step has halftone dots with a line number of 200 to 400 lines / inch and an area ratio of 3 to 30% within the image portion, and The depth of the halftone dots of the intaglio photosensitive resin printing plate for pad printing is 30 to 60 μm. A method for manufacturing an intaglio photosensitive resin printing plate for pad printing, characterized by this.

2. The method for manufacturing an intaglio photosensitive resin printing plate for pad printing according to Claim 1, wherein the photosensitive resin layer contains a synthetic polymer compound, and the synthetic polymer compound is a polyamide containing a tertiary nitrogen atom or an ammonium salt type polyamide containing a tertiary nitrogen atom.

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