JP2004262036A - Gravure printing method using gravure printing roll and water-based gravure ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gravure printing method using a gravure printing roll and a water-based gravure ink which has an FM (Frequency Modulation) screen applied on a doctor blade and can obtain a merit of the FM screen, and in which a plate fogging is hardly generated when a gravure printing using the water-based ink is performed. <P>SOLUTION: A printing area is formed by using the FM screen which leaves screen lines on a solid shadow part so as to enable to scrape the ink by the doctor blade, and dot-like recessed parts with such a size that can not transfer the ink to a non-image area are formed by a random pitch arrangement of a highlight part of the FM screen. Characters or a pattern with aimed color and color tone are printed on a base material by using water-based gravure inks consisting of five process colors such as deep blue, red, yellow added with an India ink and white. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gravure printing roll in which plate fogging is less likely to occur when gravure printing using aqueous ink is performed, and a gravure printing method performed using aqueous gravure ink.
In addition, the present invention preferably uses a gravure plate having an FM screen (Frequency Modulation Screen) applicable to offset printing or the like and having an FM screen that can be hung on a doctor blade by adding a screen line. The present invention relates to a gravure printing roll which is obtained and is less likely to cause plate fogging when gravure printing using an aqueous ink is performed, and a gravure printing method performed using an aqueous gravure ink.
[0002]
[Prior art]
Consider the mechanism by which plate fogging occurs.
In gravure printing using oil-based ink, if the plate surface is mirror-finished, the doctor blade completely scrapes off the ink adhering to the non-image area, resulting in extremely poor lubricity between the doctor blade and the plate surface. Since the blade vibrates and leaves a large amount of ink in the non-image area, plate fogging easily occurs.
Therefore, the cells are formed, chrome-plated, and then polished with paper to give a graining to the non-image area. In addition to deburring the chrome plating on the edge of the cell, the non-image area is grained. Of the doctor blade and the plate surface by incompletely scraping off the ink adhering to the non-image area with the doctor blade and leaving a small amount of oily ink in the concave part of the grain To prevent the doctor blade from vibrating, and the solvent such as toluene contained in a small amount of oil-based ink remaining in the recesses of the graining evaporates before the transfer of the ink. Transfer of ink in the image area can be avoided, thereby achieving gravure printing without plate fogging.
Therefore, plate fogging is likely to occur at a place where there are not enough concave portions in the non-image area. The concave portion of the grain plays a role of securing a condition in which ink transfer is not possible and ensuring lubricity.
[0003]
On the other hand, in gravure printing using water-based ink, gravure printing using oil-based ink is performed by forming cells shallower and reducing the transfer amount of ink, so that the evaporation rate of water and alcohol is equivalent to that of toluene or the like. A high density ink is used to ensure the required printing density even if the cells are formed shallow and the transfer amount of the ink is small.
However, in gravure printing using water-based ink, the amount of ink remaining in the recesses of the graining increases because the scraping of water-based ink attached to the non-image area by the doctor blade is inferior to oil-based ink. Moreover, since the ink is a high-concentration ink, the evaporation rate of water and alcohol contained in the ink is slower than that of toluene or the like, so that plate fogging is likely to occur.
Plate fogging also occurs where there is a grained recess in the non-image area, and graining must be performed more than enough to ensure lubricity compared to gravure printing using oil-based ink . However, if the graining is performed excessively, there is a fear that the design portion, particularly the screen line in the uppermost shadow portion, may be damaged.
[0004]
The description of the prior art in JP-A-2001-30611 is quoted as a whole.
Conventionally, in gravure printing, an organic solvent type (oil-based) ink is generally used, and the color matching of the ink used is indigo, red, yellow or a single or overprinted process color including black and white. In addition, special colors (hereinafter referred to as “special colors”) requested by customers are toned (also called “toning”) each time, or when a large amount of toning is required, printed by an ink manufacturer Manufacturer purchases and uses. In general, the printing plate is a deep printing plate (printing depth of 18 to 30 μm) with a low mesh (line number: about 175 lines) in order to satisfy the inking property and the gradation property due to the characteristics of the organic solvent type ink. ) Is used.
[0005]
For this reason, the gravure printing method using the conventional organic solvent type gravure ink has the following problems.
1. Since the ink is an organic solvent type, there are problems with the working environment as a printing plant, problems with disaster prevention, problems with the global environment due to the release of solvents to the atmosphere, and problems with residual solvents when used as food packaging films. There is.
2. In the case of an organic solvent type ink, since the plate is dried quickly and the gradation of printing is narrow, as described above, a plate having a deep plate depth and a plate made with a low mesh is used. The amount of ink used increases, which is a major factor that causes a rise in printing costs.
3. In the case of current gravure printing, in addition to single or overprinting with the above process color inks, special colors (customer-specific colors) are frequently used, so the number of colors and editions increase, and the setup time loss until printing and toning Loss increases, and in the case of special features, there is no other use, so the amount of residual ink increases, affecting not only the cost, but also discarding depending on the customer's convenience and improving from the standpoint of resource saving. is necessary.
4. Due to the recent market trends of multiple varieties, small lots, and short delivery times, cost issues are becoming increasingly severe, and environmental issues and food hygiene issues are becoming more and more important social issues. However, when an organic solvent type ink is used, there is a problem that it is difficult to meet these social needs.
[0006]
For the above reasons, a printing method using an aqueous gravure ink without using an organic solvent has attracted attention. However, in this water-based gravure ink, the problems derived from the use of the organic solvent described above are eliminated, but on the other hand, the essential drawbacks due to the water-based gravure ink are poor drying, poor re-solubility of the ink in a water solvent, and surface tension due to surface tension. Due to poor ink wetting, plates made using the same method as current organic solvent-based inks not only reduce printing speed but also cause problems such as plate fog and poor gradation, resulting in high quality printing. However, there is a disadvantage that a printed matter cannot be obtained. (End of quotation in JP-A-2001-30611)
[0007]
Conventionally, the gravure plate making method used in practice is to apply a photosensitive film on a plate making roll, form a latent image by laser exposure, develop it to form a resist mask, and etch the exposed surface of thick copper sulfate plating. Photolithography, in which the cell is formed and the resist image is removed, and finally chromium plating, engraving in which the cell is engraved on the plate making roll with an electronic engraving machine and chromium plating is applied, and other laser engraving methods is there.
[0008]
Conventionally, the gravure plate making method used in practice, such as photolithography and engraving, has been an AM screen.
FIG. 4 shows a normal gravure version of an AM screen (Amplitude Modulation Screen). In the gravure plate, the gradation expression is represented by the size of a halftone dot, and it is necessary to put the ink into a cell with a doctor and scrape off excess ink, so that the area of the screen line at the shadow portion becomes 20% to 30%. That is, the gravure plate is configured as a plate that expresses the gradation of the printed matter at about 0 to 75% with respect to the gradation of the printed matter of 0 to 100%.
[0009]
FIG. 5 shows an AM screen of an offset printing plate or a flexographic printing plate. An AM screen such as an offset printing plate also expresses a gradation expression by the size of a halftone dot, but unlike a gravure plate, a screen line is not required. Therefore, the gradation of a printed matter is approximately 0 to 100%, and the gradation of a plate is approximately 0 to 100%. Corresponds exactly.
[0010]
2. Description of the Related Art In recent years, in the field of offset printing and flexographic printing, an FM screen (Frequency Modulation Screen) system in which a gradation expression is represented by the number of minute dots as shown in FIG. 6 instead of the conventional AM screen system shown in FIG. Is being put to practical use mainly in Europe and the United States. Since the FM screen technology can obtain the resolution of the minimum drawing dot that uses the fine structure expression power, the image quality is expected to be improved even in the output from a low-resolution output device such as a printer or an on-demand printer. In gravure printing, there has been no attempt to apply the gravure printing because there is no screen line for putting ink into a cell with a doctor and scraping off excess ink.
[0011]
[Problems to be solved by the invention]
It is an object of the present invention to provide a gravure printing roll in which plate fogging is unlikely to occur when gravure printing using an aqueous ink is performed, and a gravure printing method performed using an aqueous gravure ink.
Further, the invention of the present application uses a gravure plate having an FM screen (Frequency Modulation Screen) applicable to offset printing or the like and having an FM screen that can be hung on a doctor blade by adding a screen line, and the advantages of the FM screen are obtained. It is another object of the present invention to provide a gravure printing roll that hardly causes plate fogging when performing gravure printing using an aqueous ink, and a gravure printing method performed using an aqueous gravure ink.
[0012]
[Means for Solving the Problems]
The invention described in [Claim 1] is directed to an FM screen in which an image portion is an AM screen, an FM screen in which screen lines remain in a solid shadow portion, or an FM screen in which gradation is 0 to 100%. Is any of the composite screens in which the screen lines of the solid shadow part of the screen are superimposed, and dot-shaped concave parts of a size that cannot transfer ink are formed in the pitch arrangement of the AM screen in the non-image part Or a gravure printing roll characterized by being formed in a random pitch arrangement of highlight portions of an FM screen.
The invention according to [claim 2] uses the gravure printing roll according to [claim 1] and uses an aqueous gravure ink of an appropriately selected color, or an aqueous gravure ink of a special color toned. Or by using an aqueous gravure ink consisting of five process colors of indigo, red, yellow and black and white alone, or by arbitrarily overprinting, An object of the present invention is to provide a gravure printing method using an aqueous gravure ink, wherein a character or a pattern of a color tone is printed on a base material.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The gravure printing roll according to the best mode is an FM screen in which the image area is an FM screen in which screen lines are left in a solid shadow area so that ink can be scraped off by a doctor blade. % Of the FM screen is a composite screen in which a solid screen portion of the AM screen is superimposed with a screen line of a shadow, and a dot-shaped concave portion having a size that cannot transfer ink to a non-image portion is a high screen of the FM screen. This is a configuration in which the write units are formed in a random pitch arrangement. It is preferable that the dot-shaped concave portions have a size of 3 to 8 μm square. When reducing the size of the dot-shaped concave portions, it is preferable to increase the number of distributions in inverse proportion.
Specifically, the digital information of the FM screen and the AM screen obtained by performing the FM screening so that the minimum cell has a required size with which ink transfer can be performed favorably with respect to the plate information before forming the plate. A negative mask can be formed based on digital version information obtained by superimposing digital information only on the screen line at the shadow portion of the gravure plate. Therefore, a photolithography method, a negative film formation / etching method by ink jetting, and a laser engraving method can be applied to the cell formation.
When using an FM screen, the plate depth becomes shallower than 17 μm, which is usually about 15 μm. With this configuration, the advantages of the FM screen are obtained, and plate fogging is less likely to occur when gravure printing using aqueous ink is performed. This plate cylinder is a free flow cell even if the plate depth is shallow. The occurrence of surface unevenness and the variation in print color are avoided, and high quality is obtained. On the other hand, although the screen lines are finely intermittent, unlike the intermittent screen lines in the AM screen, there is no problem in the ink scraping function by the doctor.
As an advantage of the FM screen, specifically, poor transfer of ink due to clogging of the cell in a highlight portion of a gravure plate AM screen formed by an etching method where the cell is very small. It is possible to overcome the disadvantage that the ink is not flowing so that the intersection of the screen lines of the most shadow part can be transferred to the intersection part, and the outline of the character can be an outline without jaggedness. The cells in the shadow area are shallow, making it suitable for printing using water-based inks. The advantage that FM screens are superior to AM screens from highlights to halftones is that moiré is avoided. That no line breaks occur even when printing five or more colors, City jump merit not enjoy such that inconspicuous, especially, it is possible to provide an aqueous gravure print quality.
The present invention also includes a gravure printing roll in which the image portion is an AM screen, and dot-shaped concave portions of a size that cannot transfer ink to the non-image portion are formed in a pitch arrangement of the AM screen. . With this configuration, plate fogging does not easily occur when gravure printing using aqueous ink is performed. Photolithography, an engraving method using an electronic engraving machine, a negative film formation / etching method using an inkjet method, and a laser engraving method can be applied to the cell formation.
When the image area is an AM screen, the non-image area not only has a dot-shaped recess in which ink cannot be transferred, but also has a high mesh of about 200 to 400 lines. When the plate depth is 12 to 20 μ, the plate fogging is less likely to occur when gravure printing using an aqueous ink is performed.
The method of distributing the dot-shaped concave portions in the non-image portion can be provided irrespective of the distribution method of the AM screen or the FM screen in the image portion. Since the image area is an AM screen, it is not particularly necessary to limit the non-image area to an AM screen arrangement. This gravure printing roll does not exclude application to a gravure printing method using oil-based gravure ink.
[0014]
The gravure printing method performed using the best mode aqueous gravure ink is the aqueous gravure printing method using the above-mentioned gravure printing roll and / or five process colors of indigo, red, yellow and black and white added thereto. By using ink, characters or patterns of the desired color and color tone are printed on a substrate.
Water-based gravure inks are basically produced by single or overprinting using a process color ink composed of five colors of indigo, red, yellow, and black and white, to obtain a desired color and color tone.
These five types of process color inks are prepared by adding a resin for water-based ink as a main component, a pigment and an optional additive thereto, and mixing with water or a solvent composed of water and alcohol.
The gravure printing method using the aqueous gravure ink of the present invention may use an aqueous gravure ink of an appropriately selected color, or may use a specially-colored aqueous gravure ink toned.
The toned special color water-based gravure ink can be used for part or all of the printing, and the plate making in the case of using the toned special color water-based gravure ink is the same method.
[0015]
The gravure printing plate according to the present invention is specifically shown in, for example, FIG. 1, FIG. 2, and FIG.
The plate shown in FIG. 1 is a gradation of an AM screen in which the image area is 0% to 75%, and dot-shaped concave portions of a size that cannot transfer ink are formed in the non-image area in a pitch arrangement of the AM screen. Have been. The dot-shaped recess was 8 μm square.
The plate shown in FIG. 2 is a gradation of the FM screen in which the image area is 0% to 75%, and dot-shaped concave portions of a size that cannot transfer ink are formed in the non-image area in a pitch arrangement of the AM screen. Have been.
Plate A3 shown in FIG. 3 is a combination of plate B and plate C. B, when a gradation of 0% to 100% is prepared as plate information before forming a plate, the gradation of the ink is displayed on the digital information of the FM screen obtained by performing the FM screening by the FM screening program. The non-image portion is formed by adding a dot-shaped concave portion having a size that cannot be transferred to a pitch arrangement of the AM screen. C is a screen line of the uppermost shadow portion of the AM screen obtained by performing AM screening of the plate information before forming the plate and corresponding to the shadow region from the shadow portion of the halftone portion or the shadow portion of the halftone portion. This is a display of the displayed AM screen information. Accordingly, A3 displays digital version information in which digital information of the FM screen shown in B and digital information of only the screen lines of the AM screen shown in C are superimposed.
Accordingly, the plate A3 performs FM screening of the region from the highlight to the shadow with respect to the plate information before the plate is formed, so that the minimum cells are of a required size that allows good ink transfer. In the area from the shadow portion of the halftone portion to the shadow portion of the FM screen information B (illustrated as optical information), information C (optical information) of only the screen line at the shadow portion of the gravure AM screen is displayed. (Shown as information) are superimposed on each other, so that the area from the highlight area to the halftone area is purely an FM screen and has no graininess. It is regulated to the required size that is performed well, and the mesh screen AM screen is gradually generated from the halftone part on the basis of the FM screen, and the shadow part Now fully AM screens in the region, in the non-image portion, dot-shaped recesses size is impossible metastasis ink is formed at a pitch sequence of the AM screen, and has a gravure printing plate.
This gravure printing plate is a mesh-shaped AM screen required for gravure printing in the shadow area, and the FM density of the screen is in the grid, and the optical density is uneven. In the area that shifts from the halftone area to the halftone area, the mesh-shaped AM screen gradually disappears and shifts to the dots of the FM screen. From the halftone area to the highlight area, the shadow area of the gravure version of the AM screen has the highest shadow area. Since the screen is not superimposed, the screen is purely an FM screen. In addition, since the minimum cells are regulated to a required size that allows good ink transfer, the ink transfer is good and the FM screen is excellent. Points are obtained. In the non-image area, since dot-shaped concave portions having a size that cannot transfer ink are formed in a distributed manner, lubricity between the doctor blade and the plate surface is ensured, and plate fogging is unlikely to occur.
[0016]
Embodiment 1
Using a commercially available water-based ink and water / ethanol / isopropyl alcohol / water-based polyurethane / polyvinylpyrrolidone with a diluent of 50% / 20% / 15% / 5% / 3%, the printing viscosity is Zahn cup # 3-15 seconds. The three primary colors of ink, indigo, red, and yellow plus black and white are toned, and the seven primary colors of indigo, red, and yellow plus black and white and two special colors are shown in Figure 1. As a material to be printed, gravure printing was performed at a film traveling speed of 130 m / s for OPP × 20 μm. As a result, no obstruction such as plate fogging was observed in the obtained print, and a high-quality printed matter could be obtained.
[0017]
Embodiment 2
Using a commercially available water-based ink and water / ethanol / isopropyl alcohol / water-based polyurethane / polyvinylpyrrolidone with a diluent of 50% / 20% / 15% / 5% / 3%, the printing viscosity is Zahn cup 3-15 seconds. Ink, indigo, red and yellow three primary colors plus black and white and two special colors are toned, and indigo, red and yellow three primary colors plus black and white and two special colors are shown in Fig. 2. As a material to be printed, gravure printing was performed at a film traveling speed of 130 m / s for OPP × 20 μm. As a result, no obstruction such as plate fogging was observed in the obtained print, and a high-quality printed matter could be obtained.
[0018]
Embodiment 3
Using a commercially available water-based ink and water / ethanol / isopropyl alcohol / water-based polyurethane / polyvinylpyrrolidone with a diluent of 50% / 20% / 15% / 5% / 3%, the printing viscosity is Zahn cup 3-15 seconds. The three primary colors of ink, indigo, red, and yellow plus black and white and two special colors are combined, and the seven primary colors of indigo, red, and yellow plus black and white and two special colors are shown in Figure 3. As a material to be printed, gravure printing was performed at a film traveling speed of 130 m / s for OPP × 20 μm. As a result, no obstruction such as plate fogging was observed in the obtained print, and a high-quality printed matter could be obtained.
[0019]
In Examples 2 and 3, the advantages of the FM screen were obtained. In other words, it is possible to overcome the drawback that the ink transfer is poor due to the clogging of the ink in the cell in the highlight portion where the cell is very small, in the gravure plate AM screen formed by the etching method. Ink can flow reliably at the intersection of the screen part where the ink flows so that the ink flows to the intersection part, and the outline of the character can be made outline without jaggedness. The advantages of being suitable for printing using ink and the advantages that FM screens are superior to AM screens from highlights to halftones are that moiré can be avoided and that even when printing five colors or more, No cutting, high-resolution print reproduction, density jump Benefits of such Ikoto can be enjoyed, in particular, it is possible to provide an aqueous gravure print quality.
[0020]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a gravure printing roll that hardly causes plate fogging when performing gravure printing using an aqueous ink, and a gravure printing method performed using the aqueous gravure ink.
In particular, when using a gravure plate having an FM screen that can be screened with a doctor wire by adding a screen line, it is possible to provide a gravure printing method using a gravure printing roll and an aqueous gravure ink that can obtain the advantages of the FM screen.
[Brief description of the drawings]
FIG. 1 shows a gradation according to a first embodiment of the gravure printing plate of the present invention, in which an image area is an AM screen.
FIG. 2 shows a gradation of an FM screen according to a second embodiment of the gravure printing plate of the present invention, in which an image portion is a solid shadow portion and a screen line remains.
FIG. 3 relates to a third embodiment of the gravure printing plate of the present invention, and is a composite in which a screen line of a solid shadow portion of an AM screen is superimposed on an FM screen whose image portion has a gradation of 0 to 100%. Show the screen.
FIG. 4 is a diagram showing a conventional gravure plate normal AM screen.
FIG. 5 is a diagram showing a normal AM screen used for conventional offset printing and the like.
FIG. 6 is a diagram showing an FM screen used for conventional offset printing and the like.

Claims (2)

Either the image area is an AM screen, an FM screen in which screen lines remain in a solid shadow area, or a screen line in a solid shadow area of an AM screen is superimposed on an FM screen having a gradation of 0 to 100%. Dot-shaped recesses of a size that does not allow transfer of ink to the non-image area, are formed in the pitch arrangement of the AM screen, or are random in the highlight area of the FM screen. A gravure printing roll formed in a pitch arrangement. (Claim 1) using the gravure printing roll according to, and using an aqueous gravure ink of an appropriately selected color, or using an aqueous gravure ink of a toned special color, or indigo, red, yellow and Aqueous gravure ink consisting of five process colors, including black and white, is used alone or arbitrarily overprinted to print the desired color and tone characters or patterns on the substrate. A gravure printing method using an aqueous gravure ink.

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