Gravure plate, manufacturing method therefor, and manufacturing method for gravure printed matter using same

Abstract

Provided are a gravure plate that alleviates a problem with fogging as compared to a gravure plate having a surface covered with chromium plating and a method of manufacturing the gravure plate, and a method of manufacturing a gravure printed matter including using the gravure plate. The gravure plate is a gravure plate having a cylindrical shape for printing on a web-shaped printing base material with a gravure ink, the gravure plate having a plate surface including an image area and a non-image area formed on a surface thereof, the gravure plate including: a gravure cylinder body; the image area and the non-image area formed on a surface of the gravure cylinder body; and a DLC-Si layer formed so as to cover the image area and the non-image area, wherein a contact angle of the plate surface of the gravure plate with respect to water is 70° or more, and wherein a rate of change in glossiness of the plate surface of the gravure plate before and after the printing is 3% or less.

Description

Technical Field

[0001] The present invention relates to a gravure plate having a cylindrical shape used in gravure printing, which alleviates fogging, and a method of manufacturing the gravure plate, and a method of manufacturing a gravure printed matter including using the gravure plate.Background Art

[0002] In gravure printing, minute recesses (cells) in accordance with platemaking information are formed in a cylinder to be treated having a hollow and cylindrical shape to produce a plate surface of a gravure cylinder, and an ink is filled into the cells and transferred onto a matter to be printed. In a general gravure plate having a cylindrical shape (also referred to as "gravure cylinder" or "platemaking roll"), an iron core or an aluminum core having a cylindrical shape (hollow roll) is used as a base material, a plurality of layers, such as an underlying layer and a release layer, are formed on the outer circumferential surface of the base material, and a plating layer such as a copper plating layer is formed thereon. Then, cells in accordance with platemaking information are formed in the plating layer such as the copper plating layer through use of a laser exposure device. After that, chromium plating or the like for enhancing the plate durability of the gravure cylinder is formed. Thus, platemaking (production of a plate surface) is completed.

[0003] In general, an ink used in gravure printing is an oil-based ink, but its change into an aqueous ink has been desired in view of various problems. The aqueous ink contains a large amount of water, and hence a drying load is high and a printing speed cannot be increased. In order to make a printing speed equal to that of the oil-based ink, it is necessary to increase the pigment concentration of the aqueous ink to reduce the usage amount of the aqueous ink.

[0004] However, when the pigment concentration of the aqueous ink is increased to reduce the usage amount of the aqueous ink, there is a demerit in which, when the aqueous ink passes between a gravure cylinder and a doctor blade at a non-image area and is transferred onto a web-shaped printing base material such as a film, the non-image area is also colored. This phenomenon is referred to as "fogging".

[0005] Fogging is a phenomenon that more significantly occurs as the concentration of the ink becomes higher. As described above, chromium plating is formed on a gravure cylinder surface for gravure printing to withstand the friction against the doctor blade.

[0006] For example, it is considered that the fogging is solved by a gravure printing apparatus as disclosed in Patent Literature 1. However, in the case of the gravure printing apparatus as disclosed in Patent Literature 1, a special printing apparatus, which differs from a general gravure printing apparatus, for solving the fogging is required. Accordingly, a gravure plate (gravure cylinder) capable of solving the fogging even without the gravure printing apparatus as disclosed in Patent Literature 1 has been expected.

[0007] However, the gravure plate having a surface covered with chromium plating has not been able to solve the problem with fogging even by trial and error.Citation ListPatent Literature

[0008] PTL 1: WO 2018 / 003618 A1Summary of InventionTechnical Problem

[0009] The inventors of the present invention have made extensive investigations, and as a result, have found that when the surface of a gravure plate is covered with DLC that is doped with silicon and has increased water repellency instead of chromium plating, the water repellency of the surface is increased, the property by which an ink is scraped with a doctor blade is improved, and fogging is alleviated. Thus, the inventors have completed the present invention.

[0010] That is, the present invention has been made in view of the above-mentioned problems of the related art, and an object of the present invention is to provide a gravure plate that alleviates a problem with fogging as compared to a gravure plate having a surface covered with chromium plating and a method of manufacturing the gravure plate, and a method of manufacturing a gravure printed matter including using the gravure plate.Solution to Problem

[0011] In order to solve the above-mentioned problems, a gravure plate according to one embodiment of the present invention is a gravure plate having a cylindrical shape for printing on a web-shaped printing base material with a gravure ink, the gravure plate having a plate surface including an image area and a non-image area formed on a surface thereof, the gravure plate including: a gravure cylinder body; the image area and the non-image area formed on a surface of the gravure cylinder body; and a DLC-Si layer formed so as to cover the image area and the non-image area, wherein a contact angle of the plate surface of the gravure plate with respect to water is 70° or more, and wherein a rate of change in glossiness Gs Δ (%) of the plate surface of the gravure plate before and after the printing calculated from the following equation (1) is 3% or less: Rate of change in glossiness Gs Δ = Gs 0 − Gs 1 / Gs 0 × 100 (in the equation (1), Gs 0 represents a 20° specular glossiness of the plate surface of the gravure plate before the printing measured in accordance with JIS Z 8741, and Gs 1 represents a 20° specular glossiness of the plate surface of the gravure plate after the printing measured in accordance with JIS Z 8741.)

[0012] The DLC-Si layer suitably has a thickness of from 1.0 µm to 10.0 µm.

[0013] The gravure ink is suitably an aqueous ink.

[0014] When the aqueous ink is an alcohol-free aqueous ink, a contact angle of the plate surface of the gravure plate with respect to the alcohol-free aqueous ink is suitably 30° or more.

[0015] In the gravure plate, a value (D 1 -D 0 ) calculated by subtracting a reflection density D 0 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) of the web-shaped printing base material that is unprinted from a reflection density D 1 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) at the non-image area of the web-shaped printing base material subjected to printing with a non-white aqueous ink in a printed portion of the web-shaped printing base material subjected to the printing is suitably 0.35 or less.

[0016] The plate surface of the gravure plate suitably has a Vickers hardness of 800 HV or more.

[0017] A method of manufacturing a gravure plate according to one embodiment of the present invention is a method of manufacturing a gravure plate for manufacturing the gravure plate, the method including the steps of: preparing a gravure cylinder body having an image area and a non-image area formed on a surface thereof; and covering the image area and the non-image area with DLC-Si.

[0018] A method of manufacturing a gravure printed matter according to one embodiment of the present invention is a method of manufacturing a gravure printed matter, the method including performing printing on a web-shaped printing base material through use of the gravure plate, wherein a rate of change in glossiness Gs Δ (%) of a plate surface of the gravure plate before and after the printing calculated from the following equation (1) is 3% or less: Rate of change in glossiness Gs Δ = Gs 0 − Gs 1 / Gs 0 × 100 (in the equation (1), Gs 0 represents a 20° specular glossiness of the plate surface of the gravure plate before the printing measured in accordance with JIS Z 8741, and Gs 1 represents a 20° specular glossiness of the plate surface of the gravure plate after the printing measured in accordance with JIS Z 8741.)

[0019] In the method of manufacturing a gravure printed matter, a value (D 1 -D 0 ) calculated by subtracting a reflection density D 0 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) of the web-shaped printing base material that is unprinted from a reflection density D 1 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) at the non-image area of the web-shaped printing base material subjected to printing with a non-white aqueous ink in a printed portion of the web-shaped printing base material subjected to the printing is suitably 0.35 or less.Advantageous Effects of Invention

[0020] According to the present invention, the following significant effects are achieved: the gravure plate that alleviates the problem with fogging as compared to the gravure plate having a surface covered with chromium plating and the method of manufacturing the gravure plate, and the method of manufacturing a gravure printed matter including using the gravure plate can be provided.Description of Embodiments

[0021] Embodiments of the present invention are described below. However, the embodiments are described as examples, and hence it is understood that various modifications may be made thereto without departing from the technical spirit of the present invention.

[0022] A gravure plate of the present invention is a gravure plate having a cylindrical shape for printing on a web-shaped printing base material with a gravure ink, the gravure plate having a plate surface including an image area and a non-image area formed on a surface thereof, the gravure plate including: a gravure cylinder body; the image area and the non-image area formed on a surface of the gravure cylinder body; and a DLC-Si layer formed so as to cover the image area and the non-image area.

[0023] The gravure plate of the present invention may be manufactured by a method including the steps of: preparing a gravure cylinder body having an image area and a non-image area formed on a surface thereof; and covering the image area and the non-image area with DLC-Si.

[0024] An example of manufacturing steps is described as one embodiment of the gravure plate having a cylindrical shape of the present invention.

[0025] A plate base material is first prepared. The plate base material suitably includes at least one kind of material selected from the group consisting of nickel, tungsten, chromium, titanium, gold, silver, platinum, stainless steel, iron, copper and aluminum. The plate base material is at least one kind of material, and hence may be logically an alloy. In addition, a carbon fiber-reinforced plastic (CFRP) is also applicable to the plate base material.

[0026] Next, a copper plating layer is formed on the surface of the plate base material through plating treatment. This is the gravure cylinder body. Next, a recess layer having a large number of minute recesses (gravure cells) is formed on the surface of the copper plating layer. A known method, such as an etching method (a photosensitive solution is applied to the surface of a plate cylinder and directly baked, and then the surface is etched to form gravure cells) or an electronic engraving method (a diamond engraving needle is mechanically operated by a digital signal to engrave gravure cells in a copper surface), may be used as a method of forming the recess layer. Of those, an etching method is suitable. The recesses (gravure cells) in the plate surface of the gravure plate become the image area, and an area where the recesses are not formed in the plate surface becomes the non-image area. The image area is sometimes referred to as "engraved area", and the non-image area is sometimes referred to as "non-engraved area".

[0027] Next, a DLC-Si layer is formed so as to cover the image area and the non-image area. The DLC-Si layer is a carbon film in which diamond-like carbon is doped with silicon. The formation of the DLC-Si layer is effective because a uniform film can be formed even in the recesses that are the gravure cells by a plasma CVD method. The doping amount of Si is preferably from 30 wt% to 55 wt%.

[0028] The thickness of the DLC-Si layer is preferably from 1.0 µm to 10.0 µm, more preferably from 3.0 µm to 5.0 µm.

[0029] It is preferred that an underlying metal layer of nickel or the like be arranged on the cylinder having the gravure cells formed therein prior to the arrangement of the DLC-Si layer.

[0030] The covering of the plate surface with the DLC-Si layer described above provides the gravure plate in which the water repellency of the plate surface is improved, the property by which an ink is scraped with a doctor blade is improved, and fogging is alleviated.

[0031] The water repellency may be evaluated in terms of contact angle. In the gravure plate of the present invention, the contact angle of the plate surface with respect to water is 70° or more, preferably 80° or more.

[0032] When an alcohol-free aqueous ink containing water as a main solvent is used as a gravure ink, the contact angle of the plate surface of the gravure plate with respect to the alcohol-free aqueous ink is preferably 30° or more, more preferably 40° or more. A method of measuring the contact angle may be performed in accordance with JIS R 3257.

[0033] The gravure ink used in printing using the gravure plate of the present invention is not particularly limited, and a known gravure ink may be widely used. Even when any of an oil-based ink and an aqueous ink is used as the gravure ink, the gravure plate of the present invention can significantly alleviate fogging. As described above, in recent years, a change from the oil-based ink to the aqueous ink has been desired, but the aqueous ink has involved a problem with fogging. The use of the gravure plate of the present invention can solve the problem with fogging in the aqueous ink as well as the oil-based ink. An alcohol-containing aqueous ink containing water and an alcohol as main solvents and an alcohol-free aqueous ink containing water as a main solvent and containing no alcohol may each be used as the aqueous ink. In each of the aqueous inks, the problem with fogging can be solved.

[0034] Hitherto, the presence or absence or degree of fogging has been visually observed. In particular, in the case of a white ink, it has been difficult to convert the degree of fogging into numbers. However, the inventors of the present application have found that in both a white ink and a color ink that is non-white, the degree of fogging can be converted into numbers by comparing the glossinesses of the plate surface before and after the printing.

[0035] When there is much fogging in a printed matter, the rate of change in glossiness of the plate surface before and after the printing is high. When the ink remains on the plate surface after the printing, the glossiness is lower than that before the printing (i.e., before application of the ink). The amount of the ink that passes between a doctor blade and the plate surface and remains on the plate surface can be quantified by comparing the glossinesses of the plate surface before and after the printing, though the glossiness varies depending on a material for the plate surface.

[0036] Although the rate of change in glossiness varies depending on the composition of the used ink (e.g., the presence or absence of an alcohol incorporated), the gravure plate of the present invention can significantly alleviate fogging, and the rate of change in glossiness Gs Δ (%) of the plate surface of the gravure plate before and after the printing calculated from the following equation (1) may be set to 3% or less in all the alcohol-containing aqueous ink, the alcohol-free aqueous ink and the oil-based ink: Rate of change in glossiness Gs Δ = Gs 0 − Gs 1 / Gs 0 × 100 (in the equation (1), Gs 0 represents a 20° specular glossiness of the plate surface of the gravure plate before the printing measured in accordance with JIS Z 8741, and Gs 1 represents a 20° specular glossiness of the plate surface of the gravure plate after the printing measured in accordance with JIS Z 8741.)

[0037] When the printing is performed with the non-white aqueous ink, for a printed matter in which there is much fogging, its reflection density is a high value. Accordingly, a value (D 1 -D 0 ) calculated by subtracting a value of a reflection density D 0 for a film in an unprinted state from a value of a reflection density D 1 at the non-image area of a film subjected to the printing may be evaluated as the degree of fogging.

[0038] The reflection density may be measured in accordance with JIS B 9620-1. Herein, 32 films (2 cm×2 cm) of the web-shaped printing base material are stacked, and each of the reflection densities (D 1 and D 0 ) is measured in accordance with JIS B 9620-1. When the gravure plate of the present invention is used, the difference between the reflection densities in a printed portion of the web-shaped printing base material subjected to the printing with the non-white aqueous ink (i.e., the value of degree of fogging: D 1 -D 0 ) may be set to 0.35 or less. The degree of fogging (D 1 -D 0 ) depends on the material for the printing base material, but is preferably 0.35 or less, more preferably 0.15 or less.

[0039] Further, according to the present invention, there can be provided a gravure plate sufficiently satisfying a hardness required for a gravure plate. The Vickers hardness of the plate surface of the gravure plate (i.e., the surface of the DLC-Si layer) is preferably 800 HV or more, more preferably 900 HV or more and 1,500 HV or less, still more preferably 1,000 HV or more and 1,300 HV or less.

[0040] A method of manufacturing a gravure printed matter of the present invention includes a step of performing printing on a web-shaped printing base material through use of the gravure plate to manufacture the gravure printed matter.

[0041] The web-shaped printing base material is not particularly limited, and a known web-shaped base material may be appropriately selected as required.Examples

[0042] The present invention is more specifically described below by way of Examples, but it is needless to say that Examples are only illustrative and should not be interpreted as limiting the present invention.(Example 1)<Production of Gravure Plate of the Present Invention (hereinafter referred to as "Water-repellent DLC Plate")>

[0043] A plate base material (aluminum hollow roll) having a circumference of 600 mm and a surface length of 1,100 mm was prepared, and a gravure plate having a cylindrical shape (gravure cylinder or gravure platemaking roll) described later was manufactured through use of New FX (fully automated laser gravure cylinder making system manufactured by Think Laboratory Co., Ltd.).

[0044] The plate base material (aluminum hollow roll) serving as a roll to be processed was first installed in a copper plating bath so that the hollow roll was completely immersed in a plating solution, and a 40 µm copper plating layer was formed at 30 A / dm 2< and 6.0 V. The obtained copper plating layer had no blob or pit on a plating surface, was uniform, and became a base material. The surface of the copper plating layer was polished with a dual head polisher (polisher manufactured by Think Laboratory Co., Ltd.) so that the surface of the copper plating layer became a uniform polished surface.

[0045] Next, a photosensitive material [thermal resist: TSER2104E4 (manufactured by Think Laboratory Co., Ltd.)] was applied to the surface of the roll to be processed having the copper plating layer formed thereon (with a fountain coater) and dried. The thickness of the obtained photosensitive material film was measured with a film thickness meter (F20 manufactured by FILLMETRICS, INC.) to be 4.5 µm.

[0046] Next, an image was developed through laser exposure. As the laser exposure, exposure in a predetermined pattern was performed with Laser Stream FX (manufactured by Think Laboratory Co., Ltd.) under an exposure condition of 300 mJ / cm 2< . In addition, the development was performed with a TLD developer (developer manufactured by Think Laboratory Co., Ltd.) at a developer dilution ratio (undiluted solution:water=1:7) at 24°C for 90 seconds to form a predetermined resist pattern.

[0047] Next, the copper plating layer was etched by using the formed resist pattern as an etching mask. The etching was performed through spraying at 35°C for 100 seconds through use of a cupric chloride liquid as an etchant. Subsequently, the resist of the resist pattern was peeled with sodium hydroxide at a dilution ratio of 20 g / L at 40°C for 180 seconds.

[0048] Thus, a large number of square recesses (gravure cells) each having a depth of 10 µm and a side length of 100 µm in a solid portion were formed.

[0049] Next, the cylinder having the gravure cells formed therein was installed in a nickel plating bath and half-immersed in a nickel plating solution, and a 4 µm nickel plating layer was formed at 5 A / dm 2< and 5.0 V.

[0050] Then, a DLC-Si layer was formed so as to cover the recesses (gravure cells) serving as an image area and a non-image area. The DLC-Si layer was formed by a plasma CVD method. The thickness of the DLC-Si layer was 3.0 µm. The doping amount of Si was 45 wt%. Thus, a water-repellent DLC plate according to Example 1 was produced.<Measurement of Hardness of Plate Surface>

[0051] The hardness of the plate surface of the obtained water-repellent DLC plate was measured with a Vickers hardness tester (HM-200 manufactured by Mitutoyo Corporation). As a result, the Vickers hardness was 1,200 HV.<Evaluation of Fogging>

[0052] White printing and non-white printing were each performed on a web-shaped printing base material through use of the obtained water-repellent DLC gravure plate (water-repellent DLC plate) with three kinds of gravure inks [aqueous ink A: alcohol-free aqueous gravure ink containing water as a main solvent (aqueous ink including 65% of water, 20% of a binder resin, 8% of a pigment and 7% of other additives)], aqueous ink B: alcohol-containing aqueous gravure ink containing water and an alcohol as main solvents (AQUAECOL manufactured by Toyo Ink Co., Ltd.) and oil-based ink (FINART manufactured by DIC Corporation)], and the degree of fogging was evaluated by visual observation and the following measurement. The printing was performed with a gravure printing machine manufactured by Orient Sogyo Co., Ltd. under the condition of a printing speed of 150 m / min. Non-white inks (black, cyan, magenta and yellow) other than a white ink basically exhibit the same tendency, and hence Table 1 to Table 3 show the results when cyan or magenta, which was a typical color of the non-white ink, was used.

[0053] In the visual observation, evaluation was performed according to the following evaluation criteria. The results are shown in Table 1 to Table 3. ○: fogging is absent. Δ : little fogging is present. × : fogging is present. (1) Evaluation by Measurement of Rate of Change in Glossiness

[0054] A 20° specular glossiness Gs(20°) was measured with a glossmeter (Rhopoint IQ Flex 20 manufactured by Rhopoint Instruments Ltd.) in accordance with JIS Z 8741 for the glossiness of the plate surface of the gravure plate before and after the printing, and a rate of change in glossiness Gs Δ was calculated from the above-mentioned equation (1). The measurement was performed at three portions: a central portion and both ends of the plate surface, and the average of the measured values was adopted as a measured value. A polyethylene terephthalate (PET) film was used as a web-shaped printing base material. The results are shown in Table 1 to Table 3. Table 1Aqueous ink A (alcohol free)Example 1 (Water-repellent DLC)Comparative Example 1 (Chromium)Comparative Example 2 (DLC)Gs 0 Gs 1 Gs Δ (%)Visual observationGs 0 Gs 1 Gs Δ (%)Visual observationGs 0 Gs 1 Gs Δ (%)Visual observationWhite2812752.1○86676611.5×26221019.8×Non-white (cyan)2752672.9○86873215.7×26518330.9× Table 2 Aqueous ink B (containing alcohol)Example 1 (Water-repellent DLC)Comparative Example 1 (Chromium)Comparative Example 2 (DLC)Gs 0 Gs 1 Gs Δ (%)Visual observationGs 0 Gs 1 Gs Δ (%)Visual observationGs 0 Gs 1 Gs Δ (%)Visual observationWhite2812800.4○9749274.8Δ2822655.0ΔNon-white (magenta)2852830.7○9749354.0Δ2722671.8Δ Table 3 Oil-based inkExample 1 (Water-repellent DLC)Comparative Example 1 (Chromium)Comparative Example 2 (DLC)Gs 0 Gs 1 Gs Δ (%)Visual observationGs 0 Gs 1 Gs Δ (%)Visual observationGs 0 Gs 1 Gs Δ (%)Visual observationWhite2762750.4○8668580.9○2722537.0×Non-white (magenta)2902900.0○9759552.1○2872783.1× (2) Evaluation by Difference between Reflection Densities of Web-shaped Printing Base Material before and after Printing with Non-white Aqueous Ink(2-1) Measurement of Reflection Density D 0 of Film in Unprinted State

[0055] A polyethylene terephthalate (PET) film and an oriented polypropylene (OPP) film were prepared as web-shaped printing base materials. A reflection density was measured for each of the films of 2 cm×2 cm in accordance with JIS B 9620-1. In order to increase the density value of the reflection density, 32 sheets of the respective films of 2 cm×2 cm were stacked, and the reflection density was measured with a reflection density meter (eXact Basic manufactured by X-Rite, Inc.).(2-2) Measurement of Reflection Density D 1 at Non-image Area of Film subjected to Printing

[0056] A polyethylene terephthalate (PET) film and an oriented polypropylene (OPP) film were prepared as web-shaped printing base materials. Printing was performed with each color (black, cyan, magenta, or yellow) other than white through use of the aqueous ink A (gravure printing machine manufactured by Orient Sogyo Co., Ltd., at a printing speed of 150 m / min). A reflection density was measured for the film (2 cm×2 cm) at the non-image area of each of the web-shaped printing base materials subjected to the printing in accordance with JIS B 9620-1. In order to increase the density value of the reflection density, 32 sheets of the respective films were stacked, the reflection density was measured for color at the printed portion with a reflection density meter (eXact Basic manufactured by X-Rite, Inc.), and evaluation was performed with the reflection density for the color at the printed portion.(2-3) Calculation of Degree of Fogging (D 1 -D 0 )

[0057] A value (D 1 -D 0 ) calculated as described below was adopted as a value of the degree of fogging: the value of the reflection density D 0 for the film in an unprinted state in (2-1) was subtracted from the value of the reflection density D 1 at the non-image area of the film subjected to the printing in (2-2) described above. The results of the degree of fogging (D 1 -D 0 ) of a printed matter with the non-white aqueous ink are shown in Table 4 and Table 5. Table 4D 1 -D 0 <PET>Example 1 (Water-repellent DLC)Comparative Example 1 (Chromium)Comparative Example 2 (DLC)Black0.100.460.47Cyan0.130.480.45Magenta0.070.430.41Yellow0.050.410.42 Table 5 D 1 -D 0 <OPP>Example 1 (Water-repellent DLC)Comparative Example 1 (Chromium)Comparative Example 2 (DLC)Black0.290.630.62Cyan0.300.640.65Magenta0.270.600.61Yellow0.350.660.63 <Measurement of Contact Angle>

[0058] Through use of the water-repellent DLC gravure plate (water-repellent DLC plate) produced above, the contact angles of the plate surface of the gravure plate with respect to water, the aqueous gravure ink A (non-white alcohol-free aqueous gravure ink) and the aqueous gravure ink B (non-white alcohol-containing aqueous gravure ink) were measured. A measurement method was performed in accordance with JIS R 3257. The results are shown in Table 6. Table 6Contact angle:WaterAqueous ink AAqueous ink BExample 1 (Water-repellent DLC)85°40° to 45°30° to 35°Comparative Example 1 (Chromium plating)60°20° to 25°25° to 30°Comparative Example 2 (DLC)55°20° to 25°25° to 30° (Comparative Examples 1 and 2)

[0059] In Comparative Example 1, a chromium plating gravure plate produced in the same manner as in the above-mentioned water-repellent DLC plate except that an image area and a non-image area formed on the surface of a gravure cylinder body were covered with related-art chromium plating instead of DLC-Si was prepared. The gravure plate was installed in a chromium plating bath and completely immersed in a chromium plating solution, and an 8 µm chromium plating layer was formed at 35 A / dm 2< and 6.0 V. The Vickers hardness of the plate surface of the gravure plate was 1,000 HV.

[0060] In Comparative Example 2, a DLC gravure plate in which an image area and a non-image area formed on the surface of a gravure cylinder body were covered with general DLC not doped with silicon instead of DLC-Si was prepared. The covering with the general DLC was performed by reactive sputtering. The thickness of the layer was 3 µm. In the same manner as in Example 1, an underlying metal layer of nickel having a thickness of 2 µm was formed and then the underlying metal layer of nickel was covered with DLC to form a DLC-covering layer. The Vickers hardness of the plate surface of the gravure plate was 1,500 HV.

[0061] Each of the gravure plates obtained in Comparative Examples 1 and 2 was subjected to the evaluation of fogging and the measurement of a contact angle in the same manner as in Example 1. The results are shown in Table 1 to Table 6.

[0062] As shown in Table 1 to Table 5, as a result of the measurement of the degree of fogging (visual observation, rate of change in glossiness and D 1 -D 0 ) of each of the printed matters with the aqueous inks, for all the colors in both PET and OPP films, the degree of fogging in the water-repellent DLC plate of Example 1 having formed therein the DLC-Si layer was lower than those of Comparative Examples 1 and 2.

[0063] In addition, the contact angles with respect to water and the aqueous inks in the water-repellent DLC gravure plate of Example 1 are larger than those in the chromium plating of Comparative Example 1 and the general DLC gravure plate of Comparative Example 2 as shown in Table 6. This is conceived to be effective for fogging.(Comparative Example 3)

[0064] In Comparative Example 3, a plate was produced in the same manner as in the water-repellent DLC plate of Example 1 described above except that the image area and the non-image area formed on the surface of the gravure cylinder body were covered with F-DLC in which DLC was doped with fluorine instead of DLC-Si. In the same manner as in Example 1, an underlying metal layer of nickel having a thickness of 2 µm was formed and then the underlying metal layer of nickel was covered with DLC to form a F-DLC-covering layer. A film-formation process for the F-DLC-covering layer was performed by plasma ion injection.

[0065] The thickness of the F-DLC layer was 3 µm. Fluorine-doped F-DLC was polymer-like, and the Vickers hardness was 100 HV. The hardness required as a gravure plate is generally from 800 HV to 1,000 HV. When a hardness is lower than this hardness, wear is promoted. A Vickers hardness of 100 HV did not reach the hardness required as a gravure plate at all, and was not suitable for the gravure plate.

Claims

1. A gravure plate having a cylindrical shape for printing on a web-shaped printing base material with a gravure ink, the gravure plate having a plate surface including an image area and a non-image area formed thereon, the gravure plate comprising: a gravure cylinder body; the image area and the non-image area formed on a surface of the gravure cylinder body; and a DLC-Si layer formed so as to cover the image area and the non-image area, wherein a contact angle of the plate surface of the gravure plate with respect to water is 70° or more, and wherein a rate of change in glossiness GsΔ (%) of the plate surface of the gravure plate before and after the printing calculated from the following equation (1) is 3% or less: Rate of change in glossiness Gs Δ = Gs 0 − Gs 1 / Gs 0 × 100 (in the equation (1), Gs0 represents a 20° specular glossiness of the plate surface of the gravure plate before the printing measured in accordance with JIS Z 8741, and Gs1 represents a 20° specular glossiness of the plate surface of the gravure plate after the printing measured in accordance with JIS Z 8741.)2. The gravure plate according to claim 1, wherein the DLC-Si layer has a thickness of from 1.0 µm to 10.0 µm.

3. The gravure plate according to claim 1, wherein the gravure ink is an aqueous ink.

4. The gravure plate according to claim 1, wherein a value (D1-D0) calculated by subtracting a reflection density D0 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) of the web-shaped printing base material that is unprinted from a reflection density D1 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) at the non-image area of the web-shaped printing base material subjected to printing with a non-white aqueous ink in a printed portion of the web-shaped printing base material subjected to the printing is 0.35 or less.

5. The gravure plate according to claim 3, wherein the aqueous ink is an alcohol-free aqueous ink, and wherein a contact angle of the plate surface of the gravure plate with respect to the alcohol-free aqueous ink is 30° or more.

6. The gravure plate according to claim 1, wherein the plate surface of the gravure plate has a Vickers hardness of 800 HV or more.

7. A method of manufacturing a gravure plate for manufacturing the gravure plate of any one of claims 1 to 6, the method comprising the steps of: preparing a gravure cylinder body having an image area and a non-image area formed on a surface thereof; and covering the image area and the non-image area with DLC-Si.

8. A method of manufacturing a gravure printed matter, the method comprising performing printing on a web-shaped printing base material through use of the gravure plate of any one of claims 1 to 6, wherein a rate of change in glossiness GsΔ (%) of a plate surface of the gravure plate before and after the printing calculated from the following equation (1) is 3% or less: Rate of change in glossiness Gs Δ = Gs 0 − Gs 1 / Gs 0 × 100 (in the equation (1), Gs0 represents a 20° specular glossiness of the plate surface of the gravure plate before the printing measured in accordance with JIS Z 8741, and Gs1 represents a 20° specular glossiness of the plate surface of the gravure plate after the printing measured in accordance with JIS Z 8741.)9. The method of manufacturing a gravure printed matter according to claim 8, wherein a value (D1-D0) calculated by subtracting a reflection density D0 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) of the web-shaped printing base material that is unprinted from a reflection density D1 measured in accordance with JIS B 9620-1 for a stack of 32 films (2 cm×2 cm) at the non-image area of the web-shaped printing base material subjected to printing with a non-white aqueous ink in a printed portion of the web-shaped printing base material subjected to the printing is 0.35 or less.

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